Marvel's done a remarkably solid job. They got a bit of criticism because they did it the way comics originally did it, white guys are the most important at the center of everything and then bring in minorities as things got bigger and there were more and more diverse supporting roles to fill. Not doing that is a huge part of the problem the comics have had now. They've brought in all the new readers from their Marvel NOW, and now the old readers are getting the sense that the center of the universe is colored differently now, and no one likes that. Miles is fine, as long as he's not THE Spider-Man, essentially.
What's interesting is that Marvel, working in this Eurocentric framework has managed to evolve the roles of minorities to be more than sidekicks. The kind of supporting character that Gamora is is very different from the kind of supporting character that Nick Fury is. While Falcon and War Machine are cut from the same sidekick cloth, Falcon is so compelling because he's an evolution of the Black supportive best friend archetype, in that he not only openly acknowledges his sidekick status ("I do what he does, only slower.") but he also challenges the hero with a more human less mythic perspective, and so comes to represent not the Black man, but the common man in the mythic hero's world.
Add to that that they have, in their own too-slow-for-some time seem to be poised to do Black Panther 'right' which is not only the perfect move, but it's something that seems (but is not really) unapologetically Afrocentric, which is kind of the actual desire, and not simply more lip service to something that is, in the end, a more sophisticated sidekick role. And while some would have loved to have Black Panther be an early expansion of the MCU in place of who-heard-of-this-before fare like Guardians of the Galaxy, the movie doesn't seem 'too late' at all.
For all the issues with Cage in terms of pacing and gravitas and actual social consciousness, it is also unapologetically Black, which is a breath of pretty fresh air. It did get accusations of racism (and I'd love to get into an argument about how not being EuroCENTRIC is so easily seen as being ANTIWhite, but this isn't hte forum for that), which, seeing as how that's leveled at anything Afrocentric that's published for the general audience and not just for Black folks, is apparently a good sign?
Anyway, it's hard to get mad at Marvel for handling diversity only marginally better than everyone else. Why not be mad at everyone else too? It is a stark reminder that Marvel is, at the end of the day, in it for the money. They'll expand their diversity to attract and hold as many non-Eurocentrics but not at the cost of losing their Eurocentric base. It doesn't matter how much clamor there is for Carol and T'Challa, they get to them when *they're* ready. Just before the big climactic event that sums up this whole journey that established the MCU to be what it is.
But hey... they're a helluva a lot better handled than Cyborg, John Stewart, Storm, and Bishop, that's for darn sure. And if you take the minority characters on Netflix and AoS and put them up against the CW, as cool as Cisco can be, I'm sorry, those people really have NO clue how to write as soon as they start picturing the character as being brown skinned. It's tragic, man. TRA-GIC.
All the really good ethnic characters Marvel has created are all really part of the X-Universe, which Fox owns. Bishop, Storm, Forge, The Proudstar Family, Sunfire, Sun Spot, Gladiator, Blink, ARMOR, X-23, Namor, The Shi'ar...its endless with this universe.
How ethnic are the Shi'ar on a scale of 1 to 10?
Also, Black Panther's feelings are hurt.