On one level, it could not have come at a more precipitous time. After the release of Avengers 4 in 2019, Marvel Studios' deals with some of its marquee actors are set to expire, including those of Robert Downey Jr. and Chris Evans, among others who have been around since the MCU’s big bang, and whose salaries have become astronomical.

The inbound characters, whether in stand-alone movies or fancy crossovers, are bound to give an injection of freshness to the MCU and the comic book movie genre in general, but fans should know this wish fulfillment is a double-edged sword.

For one, it's unclear whether the actors who portray fan-favorite heroes — be it Jennifer Lawrence as Mystique or Michael Fassbender as Magneto — would take part in the new movies. Both actors, who star in next summer’s X-Men: Dark Phoenix, inked expensive, one-off deals. A return in a greater Marvel universe could cost even more.

Also, Marvel head Kevin Feige has said he has 22 more movies planned to start rolling out over the next decade as Phase 4 of the MCU begins. The merging of the universe complicates that rollout not just from a development point of view, but also a distribution point of view. Just how many Marvel movies can Disney release in a year?

Insiders are already expecting casualties.

Fox’s The New Mutants is opening April 13, 2018, and director Josh Boone has a trilogy planned. But does a movie like that, with a smaller budget and rising stars, fit in a slate that includes big-budget live-action remakes such as Jungle Book and Cinderella, Star Wars movies, Pixar and Walt Disney offerings, and Avengers?

“If Disney is an NFL team, then every movie on the calendar is like a Heisman Trophy winner,” says one insider. “This raises the bar of what is a theatrical release.”

Thus, the thinking is that future installments or non-event Marvel content could be put into the silo for Disney's planned streaming service (of course, all bets are off if New Mutants becomes a hit and audience demand forces more theatrical releases).

The long-gestating Gambit movie starring Channing Tatum is finally due to begin shooting in late February 2018 for a February 2019 release. What will be the box-office threshold for Disney to consider that movie a hit, thus warranting a sequel? The answers will lie in a re-evaluation of the projects down the line to see how and if it fits into a broader Marvel strategy, according to sources.

And while some execs are already relishing rebooting (and recasting) Wolverine, a Logan spinoff centering on Wolverine's daughter X-23 is likely not going to go far at this stage.

Deadpool as an R-rated franchise seems safe for now, but Fox’s broader X-Men strategy, run by writer-producer Simon Kinberg, seems up in the air.

“[Feige] is going to be asked, ‘Do you want to continues on these developments paths?’” says one executive.

Fantastic Four, meanwhile, is a title that will have to be handled with kid gloves. A reboot would be the third iteration of the characters, and some execs professed exhaustion over a brand that never quite shined like others. Still, Spider-Man: Homecoming was the third launch of that hero, and the movie overcame brand fatigue and brand wariness when it won over audiences and critics this summer to the tune of $880 million worldwide.

And while Fox was in a position to take risks on movies like Deadpool and New Mutants, which is promising to be a darker and more horror-based take on the usual cape content. Disney is seen as more of a safe player.

Indeed, comics author and former Marvel writer Mark Millar, who co-created Kingsman and Kick-Ass, expressed concern about the future of Fox’s Marvel offering, tweeting Thursday: "A sequel to a $55M movie that made $800M is not a risk. My concern is that a gamble like Deadpool will not happen now. We'll see."

But defenders note that the X-Men will be in good hands, considering that Feige began his career as an assistant to X-Men producer Lauren Shuler Donner and earned his first credits on those movies.

"Nobody is more passionate about these characters," notes longtime X-Men composer and editor John Ottman, who got to know Feige on 2003's X2: X-Men United. "Everything he touches turns to gold, and I can’t wait to see what’s next for Marvel’s mutants.”