If you wanna see them go slower, let ASML into the Chinese market.
No harm? I don't think so. There is no such thing as letting them in for a few years unless they do something stupd enough to get kicked out again, and then we'll have to backtrack on work too. Once they establish, companies use their products and get used to it. They develop techniques unique to these machines instead of Chinese ones. Letting them in for a bit because you think it's no harm is like a former drug addict now clean and at the top of his game sitting down one night and saying there's no harm if he does crack again for just one week.
Chinese fabs are already used to ASML DUV machines and we see machines stockpiled in China for future expansion.
But all the Chinese fabs know that even if they get continued access to ASML DUV machines, there's no guarantee that they won't be sanctioned. At a minimum, we will still see Huawei and SMIC continue to work with the manufacturers to improve domestic DUV machines.
My guess is that domestic DUV machines are currently useable, but they still need a few years to work out the bugs, scale up production, and come up with a more polished version.
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And if EUV machines become available today? I do think Chinese fabs should buy as many as they need.
That doesn't stop Huawei or SMIC trying to get domestic EUV machines ready, as they know more sanctions are coming.