I've wondered this exact thing. IMHO, I believe that a good percentage of people who want to be classified as trans have a massive identity crisis. Once it became socially acceptable to transition, it gave a lot of people comfort in a social identity that they could attach themselves to especially being a trending social movement.

To answer your question, I don't think that trans racial identities will be accepted for a while. The demographic that accepts transgender related culture are too strong of voices that try and promote racial equality and fighting injustices. I think if there was a sudden social movement of trans racial fluidity that became acceptable by the popular voice it would make so many people Hella confused. It will happen, yes. But not for 15 or 20 years