ASML has no competition, you will have an easier time replacing TSMC before doing ASML. Frankly, I think they should do a hybrid approach, have TSMC do some stuff and keep refining their own Fab till they figure it out.
I think you may have overlooked the rest of it's "supply chain" -- perhaps hundreds if not thousands of other inputs necessary to run TSMC and not just doubling down on ASML's cruciality alone.