It could be argued that the last gasps of life had already been squeezed out of a proposed Floyd Mayweather Jr.-Manny Pacquiao showdown, with drug-testing demands, dollars-and-cents wrangling and the posturing of both sides gradually smothering public interest. But if the fight hadn't completely flatlined before the final seconds of the sixth round in Saturday's main event at the MGM Grand in Las Vegas, a pinpoint counter right hand from Juan Manuel Marquez abruptly pulled the plug to finish it for good.

And with that, we're left with ... what? Where does boxing go for its next "superfight," the marquee matchup that enthralls both the hard-core and casual fan? With no glorified round robin of 1980s middleweight greats to savor and no Tyson-eque one-man pillaging crew to gawk at in wonder (or horror), the sport needs a fight -- The Fight -- to marshal interest around water coolers and inside barbershops. But who will give it to us?

Below, our panel of ESPN.com experts considers the most likely candidates for boxing's next superfight.

Dan Rafael: Marquez-Pacquiao V

With the fourth fight between Manny Pacquiao and Juan Manuel Marquez in the books, we should not have to wait long for the next really big fight -- Marquez-Pacquiao V, which I expect to take place in 2013.

There are other big fights on the horizon, too. Mayweather says he will be back May 4, and I believe he'll face Robert Guerrero. Any Mayweather fight is a big one, but if Mayweather wins and Canelo Alvarez also wins a likely fight in the first half of 2013, the next megafight will be at hand in the second half of 2013: Mayweather-Alvarez. That will be a popular fight with fans and likely quite easy to make given their connections to Golden Boy Promotions.

Further down the road, maybe in the next two years, I can envision lightweight titlist Adrien Broner, who will eventually move up to junior welterweight and perhaps welterweight, headlining big pay-per-view cards as the heir apparent to Mayweather as boxing's top American star.

Kieran Mulvaney: Marquez-Pacquiao V

Superfight? Outside of a fifth Pacquiao-Marquez encounter, there is no superfight on the horizon. The biggest stars in boxing are Pacquiao, Marquez, Mayweather, Miguel Cotto and the Klitschkos, and the only possible "superfight" involving any of them is Round 43 and beyond.

Wladimir and Vitali won't fight each other, and nor should they. Cotto is all but done. The nearest equivalent, one that could happen and very well might, is Mayweather-Alvarez. That will do boffo business and be a huge event, and I'd love to see it, but whether it qualifies as a superfight on a Hagler-Hearns/Pryor-Arguello/Mayweather-Pacquiao level is a different matter.

Nigel Collins: Mayweather-Alvarez

Imagine this: A deafening cascade of boos greets Mayweather as he emerges from the tunnel and enters the MGM Grand Garden Arena wearing a sombrero, just as he did when he fought Oscar De La Hoya in 2007. But this time, instead of a Mexican-American waiting for him inside the ring, he's fighting Canelo, a Mexican national with a fighting style as fiery as his hair.

Mismatch? I'm not so sure. Don't for a second believe that Mayweather fought the way he did against Cotto to "please the fans." Floyd is slowing down -- not a lot, but enough for Cotto to rough him up. It's not unreasonable to think Alvarez could inflict considerably more damage.

Still, there are a couple of sticking points that might spoil the fun: Mayweather generally prefers faded and/or undersized foes, and Golden Boy might not want to sacrifice one of its biggest attractions. Historically, however, both problems have been overcome when the payoff is big enough, and Mayweather-Alvarez just might reach that level. Mayweather is the reigning pay-per-view champ and Alvarez has the support of the Hispanic market, boxing's most significant demographic. Right now, it doesn't get much better than that.

Eric Raskin: Mayweather-Alvarez

I have an unhealthy obsession with speculating about pay-per-view buy rates. At its 2010-2011 peak, I believe Pacquiao-Mayweather would have generated more than 3 million buys. Had Pacquiao prevailed over Marquez on Saturday and a Mayweather fight been signed for 2013, it still would have done 2.5 million. Now? Floyd-Manny is probably down all the way to 1.5 million.

And that means it's no longer the most bankable fight in boxing, because I believe Mayweather versus Alvarez, if signed for 2013 (preferably in the fall, giving it a little more time to build), could surpass the 1.5 million buy mark. Yes, Alvarez is totally unproven at the elite level. But he has the charisma and the rabid fan base to play superfight foil to Mayweather already, at age 22 -- regardless of whether he's actually a live 'dog to win.

Michael Woods: Mayweather-Broner

Everyone and their brother knows we won't get a superfight between the Brothers Klitschko.

The next-best thing would be a bout between Mayweather and Broner, the young gun potential heir to the throne as the most sellable combination of flashy talent and buzz-driving trash talk in the game, one who has said that he looks at Mayweather as a "big brother."

Broner, 23, last fought at lightweight, and one could see him rising the ranks to welterweight in two years, or less. We're guessing Floyd, who turns 36 in February, will still be gloving up then.

Bombs away, brothers ...

Bernardo Pilatti: Mayweather-Alvarez

We all know that the next megafight will see Mayweather in one of the corners, but at the same time, we must discard both of the men who are currently his most credible possible opponents. The horrible knockout suffered by Pacquiao on Saturday sent his stock reeling, while Marquez, despite notching the shocking victory, wasn't nearly impressive enough in a 2009 defeat to Mayweather to warrant a rematch.

Removing those two from the list of potential Floyd foils, the superstar club is reduced to one: Alvarez. The young 154-pound champ meets every prerequisite. He's looking for an opponent for the same date that Mayweather has in mind (May 5), his stock is higher than ever and still rising, and no one could help provide a higher possible ceiling in terms of PPV potential. We're talking about a battle that will be billed as a clash of generations, and when held on Cinco de Mayo, it'll sell like hotcakes.

Nick Peet: Donaire-Rigondeaux

Surely the biggest fight out there remains Pacquiao-Mayweather, despite the Filipino's destruction this past weekend. All that's required is for Manny to bounce back up off the canvas and face Juan Manuel for a fifth time first.

Sorry, what? Manny has left the building, you say? And not even a money-spinning showdown with former sparring partner turned recently exposed KO victim Amir Khan will tempt him back? Oh well, then, let's reconsider our options.

Short term: Look no further than this weekend's card in Houston. Both Nonito Donaire and Cuban sensation Guillermo Rigondeaux make defenses of their respective junior featherweight titles, pointing toward an inevitable showdown in 2013. Donaire has earned his place in the pound-for-pound top 10, having won world titles in every division from flyweight up and is the successor to Pacquiao's throne as sporting king of the Philippines. And whilst two-time Olympic gold medalist Rigondeaux is some way off the veteran's 30-1 slate, he's not put a foot wrong since turning pro out of Miami, picking up a world title belt before he even hit double-figure wins. Forget about a single superfight -- when these two meet, it'll be trilogy time, for sure.

Brian Campbell: Mayweather-Broner

The richest and most compelling fight that we're most likely to see in the next calendar year is clearly a Mayweather-Alvarez bout for 154-pound supremacy. But a fight on the horizon that combines both of those elements, plus the potential for compelling storylines and a more competitive result is Mayweather and rising unbeaten star Broner.

The next 18 to 24 months should catapult Broner to superstardom as he continues to climb up in weight and accept the biggest challenges available. If Mayweather remains unbeaten and active enough -- without fading from elite pound-for-pound status in the interim -- you're looking at as sexy a passing-of-the-torch fight between two sublimely talented and flamboyantly marketable fighters as can possibly be conceived in the sport, and one that breaks box office records if Broner ultimately realizes his incredible crossover potential.

Jason Langendorf: Klitschko-Price

The heavyweight division is dead. Long live the heavyweights.

Look, we've all heard the eulogy for what once was boxing's tent pole division, and although it's true that the big men have seen better days, don't underestimate the power of spectacle. Imagine a giant of a unified heavyweight champ -- one who checks in at 6-foot-6 and roughly 245 pounds -- chasing a record streak of defenses and putting all four belts on the line against an athletic and equally chiseled upstart who must look down at his opponent for an eye-to-eye prefight faceoff. Believe it or not, that's Wladimir Klitschko versus David Price, circa mid-2014. You're telling me you wouldn't drop everything to watch?

The 6-foot-8 Price, the current British and Commonwealth heavyweight champion, isn't a finished product yet, and it's possible that he won't be in time to meet Wlad before the world champ begins the inevitable slide from his prime. But unlike Seth Mitchell, the fallen U.S. heavyweight hope, or faux contenders Alexander Povetkin or Robert Helenius, Price, 29, has the size, amateur pedigree and, seemingly, the skill and sand to make a run at a slightly diminished Klitschko a couple of years from now.

By then, after Wlad has consolidated the division (he'll surely find a way to finagle the final heavyweight belt after brother Vitali retires) and has lost a little something off his reflexes, we'll be lining up to watch Price -- with a reach advantage against the notoriously jab-happy and defensive Klitschko -- test his enviable power against a chin that for years has been labeled structurally unsound. Would you dare risk missing the day Wlad went down?

Got a beef with one of our experts, or maybe you have your own ideas for a superfight? Comment below, or use #ESPNsuperfight in social media settings and we may feature your feedback.