people would just stop buying Ts, and the Chinese ran low on money as people stopped buying their imported crap, the US gov’t would have a real problem
Not really—the Federal Reserve is buying T-Bills by printing $$ out of thin air.
There's no proof of that. BB has threatened to purchase 7/10 year Treasuries in order to keep long bond rates down, but that was purely from a monetary perspective. So, for the meantime, it really is the Chinese and US citizens who are continuing to prop up the central government's finances.
While we haven't yet seen the Fed make wholesale purchases of Treasuries, it's not to say they won't.