Given scale of the current Chinese HSR program, a they could do a California line as a minor change order. Outsourcing with some "local content" rules ala transit is an interesting idea, though politics and FRA would combine to kill the idea for sure.

Of course, the Chinese don't do EIRs. We do, and for good reason (not much else would require letting the public know what's up). So even if design/build were outsourced to China there would still be plenty of room for consultants etc. to get some income out of this.