Marvel has been planning out their movies for years. They've set out a plan and they're following through with it. It's not like they can just start throwing in characters they haven't planned for yet. A lot of fans voice their requests for Marvel characters that they'd like to see on the big screen, and two of the most requested characters are Black Panther and Captain Marvel. I've always trusted that Marvel would eventually get around to introducing these characters, as soon as the cinematic universe they've built allows for it and at a time that makes sense.
While speaking with IGN, Marvel Studios president Kevin Feige was asked about bringing those two characters to the big screen, and this is what he said:
"They're both characters that we like, that development work has been done, it's continuing to be done on, and certainly it's the question I get asked more than anything else, more than Iron Man 4, more than Avengers 3. That's sort of the first time that's really happened to us, so I think that makes a difference. I think that's something we have to pay attention to... I've always said we have our plan, and it's served us very well, and there hasn't been anything that has managed to deviate or change from that based on an opinion, because opinions online change and they alter, and they are based on limited information they have to what's going on behind the scenes, but in this particular case I think it is a groundswell, and I think it means something substantial."
It's interesting to hear him hint at the fact that they could change their trajectory to include these characters in the universe sooner rather than later. Marvel currently has eleven films scheduled between now and 2019. Eight of those movies don't have titles. I guess it's not outside the realm of possibility that Black Panther and Captain Marvel could be included. We won't know for sure though until the studio makes an official announcement.