If TSMC is blacklisted by the USA, then it would cripple Apple and Qualcomm.TSMC’s only tie with US is using their market. US can try to throw their entire nation at it like they did with Huawei, but if the international community ignored their word on Huawei, why would they listen on TSMC?
If it came down to the domestic market or the US market, there’s no way they would choose the latter. Not only is it smaller (although not by much), but more importantly the public and even their own employees will lynch them.
They would have to turn to Samsung or GlobalFoundries to make processors, but they simply don't have that sort of spare production capacity.
So TSMC is fairly safe.