US should call their bluff. If Tiktok gets banned, people will complain for a little bit until people forget and move on to what's next. Why doesn't an American company make something that's practically identical? People will be all desperate for their 5 second dopamine rush that they will download anything.
As I recall, the guy who makes Pixelfed (dansup?) is also working on a vine clone called loops. It looks like the site is https://loops.video/ Doesn't appear to be operational yet.
It would be his first good instinct. But bringing back the domain is t going to bring back the magic. Vine is dead and nothing Musked is going to be any fun.