SMIC is currently running low on available capacity (load factors are in 99-100% range, which means that there's undersupply) in China itself and the priority for expansion will obviously be there as the majority of Chinese (and even foreign) companies want domestic supply chains for semiconductors. Even companies like Xiaomi and Lenovo which mostly used Western components are starting to invest in domestic supply chains after the arbitrary sanctions and hostile rhetoric by Western countries. It's only natural.
It is critical to focus on technological node here, SMIC is expanding 14-28nm capacity, not sub 7nm capacity. The latter
at the moment cannot be built in China.
ASML actually does not source that many components from the US hence the US could not enforce the export restriction that way (it is under the required 10%) which means that they ordered the Netherlands to revoke the export licenses and they complied. SMIC is in the US entity list which means that even if SMIC reached out to establish JV with some European company, the US will order to shut that down in a similar manner since the EU seems to be just following the US footsteps when it comes down to semiconductor chains.
Plus the EU would certainly benefit more from that deal since they are having trouble luring TSMC and other advanced manufacturers (capable of <= 7 nm tech processes) to build their advanced fabs in Europe. TSMC has\had some plans about European fab but for the older processes (12-14 nm), I have not heard about announcements on building 5 nm fabs and lower in Europe. On the other hand, the deal would be a net harm for the Chinese semiconductor industry since SMIC would spend a lot of money on establishing an advanced fab even in JV with some European companies (which will take probably the same amount of time that the Chinese EUV is going to take), while the EU will restrict their exports to the Chinese entities. Since the EU regards China as an enemy, then there are zero reasons for SMIC\China to agree to such a deal.
I agree that a JV endorsed by European Commision is a must, otherwise the project is doomed to fail.
I don't agree that this would be impossible to achieve. Of course US has strong lobbying in Europe Commission, but as I said there is not a single voice is Europe. The outcome of this attempt, indeed would be very uncertain....it can go both ways, it is impossible to know for sure now.
I agree that it would be very difficult for Europe to build a 5nm fab all by itself, but this is a very good advantage for SMIC, because it can offer something that Europe alone cannot and this has weight for discussions with EU commission.
Regarding who benefits more, with all the due respect, this is somewhat a bit shortsighted, SMIC should see what advantages
they have, and I guess they have a lot, but even more advantages has the vast chinese fabless ecosystem, especially in AI and other advanced technologies because they would have a trusted supplier. In my opinion it is much easier for US to block TSMC or Samsung than blocking an European JV strongly endorsed by European Comission.
Finally a brief comment on times. I think achieving state-of-the-art 5-10 years sooner it makes
a lot of difference. What US is trying to do is to slow down China, not to stop it, because they know it's impossible, but for US also slowing down of 5-10 years is a big win, and actually it is. For them it means to have the time to prepare themselves and be ready and reaming ahead of China when China reaches EUV.