(Warning: The following contains potential — albeit entirely theoretical and largely comic book based — SPOILERS for future installments of the Marvel Cinematic Universe. Proceed with whatever level of caution that suggests to you is wise.)
Now, with the rampant box office success of Marvel's recently released Captain America: Civil War, there are a whole lot of reasons to think that a fourth Captain America movie will find its way to the big screen sooner or later — $1,132,915,891 reasons and counting, in fact. With Civil War also having proven both a critical hit and an immediate fan-favorite, it seems almost inevitable that we'll be seeing Captain America 4 hit theaters sometime in Marvel's Phase 4 (a.k.a. sometime after 2019). Here's the thing, though...
Captain America 4 Could Be a Very Different Movie To What You're Imagining
Y'see, while the first trio of Captain America movies were — despite a giant pile of Avengers invading the third one — a directly connected trilogy, there's good reason to suspect that a fourth film in the franchise would be very different indeed, for three key reasons.
3. There's A Chance That Cap Is Secretly Evil
Now, when word got out a few weeks back that the comic book Captain America has secretly been a member of Hydra for his entire life, it's probably fair to say that the fan response was less than positive. As it turns out, a whole lot of people aren't instinctively thrilled with the idea of Captain America having secretly been a member of a group with close ties to both the Nazis and Imperial Japan.
That fan reaction may, of course, preclude any possibility of the comic books' latest twist making its way onto the big screen, but should the current comic book arc lead somewhere gloriously iconic (a possibility that shouldn't be written off), then there's always the chance we could see some variation of it in the MCU.
More likely, though?
2. There's A (Very Good) Chance That Cap Is Going To Die
After all, the comic book ending to Marvel's Civil War (in which Cap very much died) may not have been replicated on the big screen in Captain America: Civil War, but that doesn't mean it won't be sometime over the next few years. After all, with those rumors of Chris Evans's plans to retire from the role in the near future refusing to go away, there remains the distinct possibility that Avengers: Infinity War could end with a variation on Cap's comic book death.
If so, though, there's little reason to suspect that such a move would actually mean the end of the Captain America franchise. Instead, it would increase the chances of the MCU imitating its comic book inspiration in yet another way: By introducing a shiny, new Captain America. Here's the thing, though...
1. There Could Easily Be Two (Or Three!) Captain Americas By The Time A Sequel Rolls Around
Y'see, there have actually been several Captain America's running around the Marvel comic book universe in recent years, with both Bucky "The Winter Soldier" Barnes and Sam "The Falcon" Wilson having donned the iconic duds for extended periods of time. In fact, as of right now, there are actually two Captain Americas, with both Steve Rogers and Sam Wilson rocking the red white and blue.
As such, the most likely plotline for Captain America 4 might just be less Captain America, and more Captain Americas (or should that be Captains America?). It's entirely possible that we could see a still untrusted by the government Bucky Barnes don the uniform, as would surely be Cap's last wish (as it was in the comic books), and then watch as the government asks the more dependable Sam Wilson to do the same. Captain America v Captain America, anyone?
Perhaps even with this handsome son of a gun returning in the movie's final act...
...leaving us with three whole Captain Americas, and one heck of an interesting second trilogy of movies.