ASML is going to remain a monopoly and whatever Chinese alternative that there may be is going to stay in China for the foreseeable future.
However because the Chinese electronics industry is so big and they rely so much on imports, when they are building alternatives to the US-controlled semiconductor supply chain (ASML, Applied Materials, TSMC etc.), it will matter at one point for ASML even if the Chinese tools and final products are never exported.
Seriously, try to design anything non-trivial without a TI part anywhere. Even in China, foreign brands are everywhere in electronics, and much of it is imported.
There's a lot of scope left for China to penetrate the "low end" semiconductor (and other electronic parts) market as well.
>> ASML is going to remain a monopoly and whatever Chinese alternative that there may be is going to stay in China.
Suppose China develops a cheaper way to produce the EUV light and sells the tools for half what ASML does. They might sell to others just to become the leader.
Or they skip EUV all together and go straight to xray.
IMO that is the real threat to both ASML and the current Western supply chain. By forcing China out you make it very likely they will choose to leap-frog instead of try play catch-up. They did it with EVs there is a very good chance they do it with semiconductors also.
It would need entirely new resist, lenses, associated inspection, cleaning and repair equipment etc.
Which sounds like a terrible idea until you realize they would need all the same stuff for EUV except when they are done they would still be ~10-15 years behind.
Building an entirely new process based on xray would be challenging certainly but not that much more challenging from going from where they are to EUV.
I don't think that applies to technology that no one else really has. China is great at bringing down cost of something the west can already produce...they just flood the market with lower cost versions that destroy the business case for developing those products in the west. Solar panels, rare earth refinement, drones, EVs, etc...the west can do all of that, but if they undercut the market, they won't and eventually those capabilities stagnate.
But if they have something the west doesn't have, why sell it and up an advantage? We aren't friends. There are plenty of things the Chinese aren't selling to the west already (real innovations), and vice versa.
They might want to sell... but who might (want to) buy, outside of Russia and maybe India? The Western world is already decoupling from China and I think it's completely infeasible that anyone wants to create new ties to China.
Anyone is a stretch, not everyone is so keen to take the US side in the trade war at their own expense. South American and African trade is still pretty brisk and growing as far as I know. Mostly they don't have the possibility of onshoring industries that they didn't have in the first place, as opposed to the West where it's more like attempting to re-shore previously-discarded capability. So they don't really have a horse in the race, they're going to be importing anyway.
"Anyone planning a major semiconductor fab in the 2020s", then quite probably, yes.
Everyone wants to do business with China, because China has money (which we gave them) and everyone wants that money (which will ultimately go back to them with change and interest).
Lest we forget, Japan and South Korea are mulling a free trade agreement[1] with China.
Anyone following US-led sanctions against China are doing so dragging their feet and groaning in annoyance.