Any United States sanctions and bans on SMIC will be very damaging move. It effects will be long term and permanent for at least a generation, politically and economically speaking.
Technically speaking, no, this will be not the case, as that would be a great for China IC industries. This is like the two bombs and one satellite again, but this time already maybe 75% there at least!
A ban like this, would be close to a wartime sort of ban. No one goes around enforcing patents in wartime, even in fake wartime like now, who is going around enforcing patents when the Chinese will reverse engineer every single piece of IC machinery now.
This break in the technology chain, which is a break in technology relationships, will mean no patents enforcement, and no more business for some, like US companies. They will not be allowed to sell.
This is a true statement, that the United States will not sell semiconductors to the Chinese military. Now the United States has been moving a position not to sell semiconductors and related equipment to Chinese companies in strictly civilian consumer goods.
Naturally, China under the CCP will take that next step and will not care how long it will take to build two bombs and one satellite. In the case of the IC industry to bring it closer to TSMC, Samsung, ASLM, let's see in 5 years. Low end already done.
Bwahahahahahaha!