The mighty Marvel Cinematic Universe is full of connections. Even people who aren't deep nerds like us (and I'm assuming that if you're reading an article with a title as boring as this one you're a deep nerd) get excited when The Falcon shows up in Ant-Man or Cap cameos in Thor: The Dark World. People love these connections, and they're one of the secrets to the vitality of the MCU. But it's hard not to feel like the TV shows stand off to the side, not quite existing in the same space as the movies. We have seen some crossover - Jaime Alexander popped up as Sif in a couple of episodes of Agents of SHIELD and Samuel L Jackson did a walk-on on that show as well, but that's been about it. The crossovers certainly have not gone the other way (Peggy Carter, introduced in the movies, does not count).
But with the introduction of legit superheroes on Netflix could that change? By this time next year we'll have Daredevil, Elektra, The Punisher, Luke Cage and Jessica Jones introduced and active in the MCU - is it too much to hope for them to show up in Captain America: Civil War?
Probably. There are a couple of reasons for this, one of which is that Marvel TV and Marvel Studios operate somewhat independently. But the main reason is not business related - it's about time.
The main problem is that the production schedules for movies and TV shows are very, very different. The movies operate more than a year in advance, usually - whatever you see onscreen in Captain America: Civil War in May will largely have been locked down before they started shooting a few months ago, so 16 to 18 months before release. They were well into production as Daredevil began breaking stories and figuring out the details of the second season. As Civil War wraps, Daredevil season two is just getting underway. And Agents of SHIELD season three hasn't even started... and that will be all but finished by the time Civil War is released!
Those differing production timelines mean that continuity - something Marvel cares about - becomes an issue. Yes, they could bring in Charlie Cox to put on his Daredevil suit for Civil War, but will that be his Daredevil suit in season 2? Will he get a new one midway through? Do the showrunners want Daredevil hobnobbing with Captain America at all? Do the showrunners know where they're leaving Daredevil at the end of the season, or are those stories still being broken as the show goes into production?
Remember that Marvel has a simple rule: the MCU takes place in real time. That means that, give or take a few weeks, Ant-Man happened around its release date, which means it happened a few months after The Avengers wrecked Sokovia (and that event is referenced in the movie). Since we know that Spider-Man will show up as an existing character in Civil War it makes sense that he can be referenced now in Ant-Man. But when Civil War comes out, where will it be in relation to Daredevil season two? That isn't even dated yet, so would you want the Daredevil who shows up in Civil War to be a post-season one Daredevil or post-season two?
It's easier to plop a movie character into the TV show, because the story of the movies are pretty well planned out before the show goes into production, but that's a harder row to hoe. You may get Chris Evans to come do a favor and show up in Thor: The Dark World, but is he likely to do the same for Jessica Jones? Let's not even reduce ourselves to wondering if he would show up on Agents of SHIELD. (He may very well be willing to do it for Agent Carter, though - anybody who follows Hayley Atwell on Twitter can see that she and Evans are terrific pals. A Captain America dream sequence in Agent Carter season two? BE STILL MY HEART)
These things make crossovers difficult, but not impossible. Will we ever see a TV character show up in a post-credit stinger? I can't imagine why not; after all, the second Ant-Man stinger was shot on the set of Civil War, which is still in production. Marvel turns those around very quickly, and if TV and movies get on the phone I'm sure they can work something out. Also if Daredevil is any indication the Netflix shows will be harder for the movies to ignore than SHIELD; people really got into Daredevil and it was a major hit for Netflix. Depending on when Daredevil season two is airing it could be possible to see Frank Castle suiting up in the second post-credits stinger of Civil War, say.
I also suspect that come Avengers: Infinity War Part II we'll see the entire Marvel Cinematic Universe onscreen at one point, probably in a kind of montage that spans the breadth of it all, bringing back every actor they can get to agree to do a two second cameo (maybe looking off camera in awe or horror as Thanos erases reality or something).
Over the last few years the one thing I have learned about Marvel is to never say never. This problem with timing and continuity was explained to me by a Marvel insider, but that same insider told me that rather than find this problem insurmountable the company looks at it as something they'll surmount when they need to do so. After all, these are the guys who worked with Sony to get Spider-Man back in their universe. With their standard schedule of additional photography and willingness to add elements to their films up to and beyond the premiere, anything is possible in the Marvel Cinematic Universe. But for the moment it seems like bringing TV characters to the big screen isn't a major priority... until it is.