Analysts and investors have long debated the merits of one question in particular: Would Facebook (FB) - Get Report ever try to buy Snap (SNAP) - Get Report ? For now, the answer seems to be that it's possible, but unlikely.

FBN Securities analyst Shebly Seyrafi has made the case for why such a deal would make sense and the main reason is that, in doing so, Facebook would eliminate one of the "very few" long-term threats to its business. Data has shown that Facebook is losing a great deal of its teenage users as they move over to Snapchat -- a trend that the social media giant shouldn't ignore.

Shares of Snap were up 0.2% to $22.88 on Thursday, while those of Facebook were up 0.4% to $138.24.

"Facebook should take the Snap threat very seriously, particularly since there are predictions of much stronger growth at Snap outside the 12-to-24 age cohort which, so far, has been the company's key demographic focus," said Seyrafi, who initiated shares of Snap with a Sector Perform rating and $23 price target. So far, no analysts have given Snap a Buy rating.

Snap's stock price could continue to fall, forcing the company to explore alternatives such as being acquired, as Twitter (TWTR) - Get Report has, Seyrafi said. And at a lower stock price, Facebook could be willing to pay at least $20 billion (or $14 a share) for Snap. It wouldn't be the first time that Facebook has tried to scoop up its formidable social media rival -- Facebook in 2013 offered $3 billion to buy Snap (then Snapchat), but the bid was later rejected. Facebook has also made similar large deals in the past for hot start-ups, shelling out $21.8 billion for WhatsApp in 2014.

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Since then, Facebook's modus operandi has been to clone many of Snapchat's most popular features -- including its ephemeral Stories, geofilters and lenses, as well as its vertical video advertisements.

But this is where a deal between Facebook and Snap starts to look less likely, according to several analysts. If Facebook is able to clone Snapchat Stories and other features, then why would it need to acquire the whole company?

"While Facebook has more than $29 billion in cash and can access additional capital with ease, I'm not sure why it would pay a huge premium to purchase Snap, given that it can basically copy Snap's features," said Morningstar analyst Ali Mogharabi by email. "The potential return may not be attractive enough to justify such an acquisition."

It's also not a given that Snap can steal ad dollars away from Alphabet's (GOOGL) - Get Report Google or Facebook, Mogharabi said. And Snap may eventually face a natural limit in user engagement, time spent and the number of new users it can add.

"Such a limit is likely to impact Facebook (which has a much larger user base) less than it may impact Snap (which has a smaller user base and is still trying to grow it)," Mogharabi explained.

These indicators mean that Snap may shape up to be less of a threat to Facebook after all.

Even if Facebook does decide to pursue a deal with Snap, if Snap co-founders Evan Spiegel and Bobby Murphy decide they aren't interested, it's pretty much a moot point. In its IPO, Snap issued Class A, non-voting shares, leaving the majority of the control in Snap to Spiegel and Murphy. So any shareholder or activist pressure on Snap would likely be ineffective, as would a proxy contest initiated by Facebook, said David Berger, a partner at the Silicon Valley law firm Wilson Sonsini.

"The likelihood that Facebook would generate activist pressure for Snapchat is slim to none," Berger, who attended a meeting of the SEC's Investor Advisory Committee on Thursday, where regulators questioned Snap's non-voting share structure.

Additionally, it's nearly impossible for activist investors to target companies with non-voting class stock, giving a company's founders a great deal of power in assembling its board and making strategic decisions, among other things.

"I don't think they want to sell and that [shareholder structure is] the most important barrier," said Loup Ventures analyst Doug Clinton, adding that many other Silicon Valley tech giants including Facebook, Google and Tesla (TSLA) - Get Report also have restrictive voting structures.

One scenario where Snap could consider being acquired would be if it ever saw a significant slowdown in users, but at that point Facebook or another large company (Seyrafi also mentioned Comcast (CMCSA) - Get Report) would likely lose interest in pursuing a deal. Snap is expected to generate negative free cash flow in the near term, but if they don't turn a profit soon, the company could begin to resemble the struggling Twitter (TWTR) - Get Report and open itself up to an acquisition, Seyrafi noted.

That said, Snap shareholders are largely betting on Spiegel's ability to execute his ambitious vision for the company and that vision would likely be deterred if Snap agreed to be acquired.

"I think they have a lot that they want to accomplish as an independent company," Clinton said.