I do think there's a second wave of frameworks coming, because Django/Flask are showing their age a bit. Sanic is/was really popular and I think FastAPI is really promising.
Sanic is indeed just an ASGI version of Flask, though who knows how it will develop in the future - but FastAPI is a whole other beast. Also, Django is adding support for ASGI so no, that's not the main difference I wanted to point out.