The end of Phase 2 left the MCU in a strange place. Introducing the first non-American superhero in the form of Black Panther suggests that the movies are going to take a more international flavour from now on, something that introducing the Ancient One in Dr. Strange certainly hints at. The situation is more complex, with the official Avengers team potentially down to being Team Iron Man and nothing else, and Team Cap in the wind, presumably spreading out all over the globe to deal with stuff under the radar. Given that Thor and Hulk are presumably off planet at this point, I assume we won't see them get involved in the events on Earth until Avengers 3, at which point it will be interesting to see which way they go on the Sokovia Accords.
In the meantime, we should remember that Marvel actually has a lot of work to do to get the stage set for Thanos' invasion. We still do not know where two of the Infinity Stones are (Time and Soul respectively), and as the details of the second Guardians, film are still shrouded in secrecy it is unclear where we will see them. Tempting as it is to assume that the Soul Stone will appear in Dr. Strange, if Adam Warlock turns up in Guardians, we will have to see as traditionally the artefact is associated with him. Also, bear in mind that so far Thanos has none of the Infinity Stones in his possession and that as a result we have a handful of movies to see him assemble the Infinity Gauntlet. It may be that the first segment of the Infinity War films will be dedicated to that, but I feel that we need to see the Gauntlet completed by the end of the first film, presumably with a shot of a defeated Avengers team at his feet (so that we can have a 'putting the band back together' arc in the next one).
There are a handful of things I'd really like to see in the Marvel films, though, both from a world building point of view and from pure geekery.
1) More International Heroes
We have seen American heroes, and of course the Asgardians, but really outside of the USA, super powered beings are vanishingly rare. I hope that we will be treated to a growing number of heroes from the rest of the world, even if it's only in cameo roles. I have always felt that it's very silly that there's so little activity elsewhere. It would be nice to see a level of Real Politick here, with Russia, China, Germany, etc, striving to have their own champions. This would make particular sense now that the politicians have got involved and put restrictions on the Avengers. From a comics point of view, this would not be particularly hard, especially given the way that Marvel have shown themselves willing to adapt their heroes to the big and little screens.
Of course, this also chimes with my desire to see a British hero in the films. As Captain Britain may be tied up with the X-Men deal Marvel signed with Fox in the late 1990s, it would be great to see Union Jack, perhaps as a British version of Black Widow or Captain America, deeply ensconced with the UK's own version of Shield (and a World War 2 set film with Jack working secretly while Cap gets all the headlines would be perfect and explain why they do not know each other). It would also allow Marvel to introduce Alpha Flight, Canada's team of superhumans, and in a move that would surely please the Chinese market, to make the Ascendants part of the universe.
2) The UN Meddling
Linked to the above point, and to the comment earlier about how few Avengers there are now, it would be lovely to see the UN bolstering their numbers through a series of interventions, perhaps insisting that a new Captain America, one with the White House's approval steps up to the team, or that someone like the Abomination be drafted so that he can work his sentence off via superheroics.
It would also be good to see Tony Stark (or is that Stank?) being forced to work more at bureaucracy and office politics to get his way around the likes of Thaddeus Ross. What might be even more fun is if they were to introduce a team of ringers, characters like Thunderstrike or Red Hulk, so that as viewers we see them get defeated and then have the real deals take up the baton in the second Infinity War film.
A quick note on if they do go this route (which is unlikely, I am just spouting off on the internet after all), I suspect that the new Cap would neither be Falcon or Winter Soldier, but rather someone like US Agent, a man very much of this time rather than a man out of it. We have seen a heroic Captain who goes against the government when he has to, doing what is just rather than necessarily legal. It would a change of scene, possibly, not a welcome one, to see an alternative and to have it firmly established that he is not really meant to be liked.
3) The Nova Corp
We saw them in Guardians, but the Novas were not really like they are in the comics at all, where far from flying little ships they have super suits and are basically the Green Lanterns of the Marvel Universe. It would be so cool to see them introduce that into the MCU, I would seriously squeal if they introduced even a prototype suit in the next Guardians film.
4) The Elders of the Universe
It would add a new dimensinon the universe and be just a cute little nod to the universe's legacy.
5) Winter Widow
One of my wife's desires, rather than strictly being one of mine, in the comics there's a romantic relationship between the Winter Soldier and Black Widow, and she would very much like to see that on screen. Perhaps in the Black Widow film?
6) More Villains
While the bad guys we have seen so far are great, it would be nice to see more and not necessarily the ones who die at the end of the film. There are so many good villains out there (and it would be nice to see Marvel move away from using their staples of Thanos and Hydra, because that is starting to feel a touch old). The likes of the High Evolutionary would be nice to see, perhaps as a way to examine Scarlet Witch's power more?
Anyway that's my list, what would you like to see?