Well, they would be seriously hurt. However, does that matter when almost every tech company (including Qualcomm, MediaTek, AMD, Apple, ARM, Broadcom, Marvell, Nvidia, Intel, so forth) would also be harmed?
TSMC going down is basically the MAD (Mutually Assured Destruction) of tech companies. Kind of a single point of failure. Intel would probably weather it best but would still be hurt because they need TSMC for some products. Plus, well, in the event of TSMC's destruction (most likely by a Chinese invasion), Intel might raise prices considerably or even stop sale to consumers especially as their chips would now have major strategic value for government operations. NVIDIA might also survive by reviving older products which can be manufactured by Samsung in Korea, but same situation about the strategic value there, and getting chips from Korea to US might be difficult in such a conflict.