Of course TikTok itself can decide to block all connections from the US to make their point. They will do that for just a few days, if at all. Trump has already declared that he might sign an Executive Order to delay the ban by 90 days in his usual non-committal nonsense way of talking (possibly paywalled https://www.washingtonpost.com/technology/2025/01/18/trump-tiktok-ban-90-day-reprieve/ )