Marvel Studios basically created this problem for themselves. Every time they prepare to unveil a new movie, fans (and fanboy journalists) turn their collective attentions to the future, wondering what's to come. And it's Marvel who started this process, revealing all of the titles in their Phase 2 and Phase 3 to both whet appetites and whip up a frenzy of anticipation. There will be 10 films total in Marvel Phase 3, starting with Captain America: Civil War and running through an untitled Avengers film in 2019. What will come after that? Marvel President Kevin Feige opened up about the studio's approach to Phase 4, saying:

I think anything is possible. I think absolutely you've seen our model this year [and] last year that we like a new adventure in the ongoing stories of existing characters, and then something completely new and completely different. ... We know what we'd like [our announced movies] to be for 2020. Over the years, where we're aiming, we've been lucky enough that it's usually been the same thing but we always leave ourselves the opportunity to bob and weave and adapt if we have to. But we know where we're headed for 2020, and we have ideas and were beginning to solidify the years beyond that.

Marvel's Inhumans, right now, is the only title associated with Phase 4 that may still happen, but even the future of that project lies in doubt because there has been no real progress -- reported progress, anyway -- on its development.

So, taking what Kevin Feige has to say to Collider about a mix of new adventures for existing characters as well as stories that are "completely different," this means that we're likely looking at sequels for heroes who have been introduced in Phase Three. Marvel Studios has three dates circled for Phase Four movies in 2010: May 1; July 10; and November 6. And by the time that we reach them, characters that COULD be due for sequels would include Doctor Strange (Benedict Cumberbatch), Spider-Man (Tom Holland), Black Panther (Chadwick Boseman) and Captain Marvel (Brie Larson). Scott Derrickson and Tom Holland both have discussed sequel plans already being underway for their respective franchises. And that's not ever scratching the surface of the existing Avengers, from Iron Man and Thor to Captain America or the Hulk. And what of that Black Widow movie they are flirting with? Or a third Ant-Man flick?

As you can see, the possibilities are endless, and this is even WITH Marvel increasing its annual output to three movies -- something they once were opposed to, as little as a few years ago. You should bookmark this link right here, as it has all the relevant information on Upcoming Marvel Movies, and we update it frequently. Doctor Strange, in the meantime, opens in theaters on November 4.