What if China becomes self-sufficient enough to no longer rely on Taiwanese Fabs, and hence having no issues with those Fabs getting destroyed. That would put China as the leader once and for all.

First, the US has advanced fab capabilities and in case of a need can develop them further. On the other side, China will suffer a Russia style blockback while caught up in a nasty war with Taiwan.

Totally possible, but the second order effects are much more complex than "leader once for all". The path for victory for China is not war despite the west, but a war when the west would not care.