No government, even Nixon's, could roll back black civil rights, but they could and did introduce discriminatory bills and witch hunts (the War on Drugs) which led to economic devastation for many black communities.
One parallel I can see is that they make it so religious people don't have to serve gays. But that only hurts religious people in the end. And the social backlash would probably make said religious-owned businesses unviable.
There's also the prospect that they could cut funding of things pertaining to LGBT health like HIV research, but we saw what happened when Pence tried it in Indiana and it was unconscionable, I doubt he'd try it on the national level.
but I won't get my hopes up 