With an alleged 150 million users in the US, there will probably be protests against such a decision.
Of more importance how will it impact competition and applications if the US sets a precedence to ban apps the state does not want their citizens to see.
Protests over TikTok will blow over. It takes a lot more than a protest for societies to blink, and we've seen many many much more serious protests testify to that. People will get upset when something in their daily routine gets taken away and then almost all of them they'll get over it because it's not really consequential to most people.
> how will it impact competition and applications if the US sets a precedence to ban [select foreign] apps.
As for competion -- well, I'd it to embolden local companies to compete more vigorously in other domains where Chinese apps might be targetted for a ban, and encourage lobbyists to make that happen.
That's not a win for everybody, but it's also not a loss for everybody.
Although I could care less if it's banned or not, I think the world would be a better place without it. Likewise for Instagram, et al.