It's also a relatively fragile pipeline. People can't just wait a few years when they hit transition points; universities have already massively curtailed their

It's also a relatively fragile pipeline. People can't just wait a few years when they hit transition points; universities have already massively curtailed their enrollment for the incoming graduate class because of their attempts to completely shut off grants both new and existing, new PhDs are going to have a tough time getting Post Doc positions and post docs are going to have a hard time getting faculty positions. All those people need jobs so they'll have to either find temporary work and hope to get back on the track after that (competing against all the people who had to do the same over the next 4 years unless they're stopped soon) or go overseas.