Am I the only one who is thinking that it isn't the point right now.
Disney have spent a not inconsiderable time in recent years moving away from romantic storylines (even in Frozen the romance is secondary to the main storyline). They've been exploring some really difficult controversial subjects (Zootropolis) and very different animation styles (Big hero six, fantasia 2000, paper man short).
Essentially they've spent time examining there own history with a critically reverential eye. And they have gone back to innovating in the areas that Disney have always been into innovating (animation itself).
Don't get me wrong I'd love to see a gay or disabled character but the trick would be to make it happen without it seeming forced and without resorting to unhelpful stereotypes. I suspect that would only happen during development when the opportunity to tell a very different story appears eg when the Let it go song was written, Elsa changed from being the villIan of the piece and the story shifted organically to the relationship between the two sisters. Arguably the good dinosaur introduces elements of anxiety in the same way as someone mentioned earlier Frozen does
Many of the modern disney films have spent time talking about redemption and renewal (reflection of where disney are/were in they're own history maybe). Recent/new generation "heroes" have frequently been characters who have the capacity to do harm but ultimately don't (Stitch, Elsa, wreckit Ralph, Bayamax, sadness, the predators). It isnt a natural set up for a gay or disabled character as there is nothing wrong or harmful with being gay or disabled in the first place.
Zootroplis was a definite departure in terms of theme. The redemption and renewal had already happened before the film it was about the problems with sustaining.I think though you could read predators and prey as any relationship between the majority (the ones with the power to eat you up) and minority, which is applicable to race, disability gender etc. Maybe not explicit enough for some but the issues of being a minority are there.
Pixar have obliquely tackled the subject of disability more from the point of view of characters who find themselves in situations they weren't expecting to be in because physically something has gone wrong (even though they are cars and planes). Doc Hudson to a lesser extent, and also Dusty in Fire and rescue. (Although they retreat from it being permanent and give him a new gear box in the end.) Pixar has tended to be allowed to be a little less conservative.
Disney have never been socially innovative in their films and they have still got to appeal to a majorly conservative America. What is interesting is seeing what they are still managing to slide in there.
In short forcing it just wouldn't work.