Yes and no. If NVIDIA loses access to TSMC due to geopolitical events, presumedly their competitors do too. There might be a couple years where they face increased competition from their own used market if they're unable to produce chis competitive with the previous generations', but at some point Samsung et. al. will catch up on capability and capacity, and NVIDIA will be as well positioned relative to their competitors to take advantage of that as they are today. The only case where this would be significantly different is if one of NVIDIA's major competitors was independent of TSMC and thus could use the lean times for NVIDIA to leapfrog them; but that would require considering Intel a real competitor.
Arguably in this sense their only competitors would be screwed even harder. The last non-TSMC GPU that AMD has released is based on GloFo 12nm/14nm, NVIDIA would actually be ahead with Samsung 8nm. Intel's only dGPUs are TSMC as well, they flatly don't have a product without TSMC.
I think Intel's advantage in this hypothetical is access to foundry space. Porting their current CPU designs from TSMC to their own foundry is non-trivial (although it can't be that hard -- their integrated graphics are fabbed on their own process, and share quite a bit with their discrete units), but at least having completed that effort they have somewhere to go, instead of fighting over what will be extremely over-subscribed Samsung fabs.
NVIDIA also depends on not getting the Micron treatment from China. Or even not having China take a particularly hard line on their Micron policy and disallowing NVIDIA to import Micron chips to use in their manufacturing produce for export from China.
Yes and no. If NVIDIA loses access to TSMC due to geopolitical events, presumedly their competitors do too. There might be a couple years where they face increased competition from their own used market if they're unable to produce chis competitive with the previous generations', but at some point Samsung et. al. will catch up on capability and capacity, and NVIDIA will be as well positioned relative to their competitors to take advantage of that as they are today. The only case where this would be significantly different is if one of NVIDIA's major competitors was independent of TSMC and thus could use the lean times for NVIDIA to leapfrog them; but that would require considering Intel a real competitor.