If they take the center module I believe NASA has a replacement stored in a warehouse encase the Russians failed to get their module launched
The Russian half is junk anyway.
And Mr Musk sez “Huh ... We’re only launching one every week. Plenty of room in the manifest for a few more.”
The US half controls the station attitude. We didn’t want to share the CMG technology with Russia. The Russian half controls all the orbit adjust thrusting. Each half is monitored and control by the ground controllers of their respective country. If either country pulls out it falls apart.
Good!
The space station is an expensive as hell political project. It does return science but at great cost. This same science can be done at a fraction of the cost via unmanned science packages in orbit.
De orbit it over the Pacific and watch the light show.