Over at the European Tribune DoDo offers an excellent look at how globalization has affected the manufacturing of HSR trainsets. This clearly has implications for our own high speed rail system, since most of the manufacturers who would provide trainsets for California HSR are based in other countries (though I hope and expect they will produce the cars here in CA). Anyhow, it's a very good read and surveys not only the technical aspects of HSR technology but the political considerations behind them, how shifting markets in both Europe and Asia have driven innovation. For example:
Alstom's ambitions in particular were long hampered by SNCF's unwillingness to order the AGV: they preferred the lower price and reliability of the TGV (and the higher capacity of the double-deck Duplex) over (relatively minor) improvements in performance.
The AGV, you'll recall, was the trainset that Fiona Ma rode in 2007, a trip that did much to raise the profile of HSR here in California. Had SNCF been willing to order the AGV it could have made that technology a more readily available option to us in California. True, that option is still there, but it's my belief that the CHSRA will - rightly, in my view - prefer to go with a more commonplace trainset than something untested and new.
Perhaps it will be Spain that pushes the envelope most effectively:
Finally, there is the above mentioned announced threat to everyone from Spain, the Talgo AVRIL. To cut Madrid-Barcelona times to 1h45m(!), the targeted service top speed is 380 km/h. With Talgo's expertise, this should be considered with more seriousness than China's ambition -- but not without doubts. Talgo named its current top product Talgo 350, but it is certified for only 330 km/h (with insufficient power and ride quality among the likely reasons).
380 km/h is about 236 mph, which would achieve the CHSRA's stated goal of 220 mph top speeds on the line. If Talgo can deliver that service to RENFE then it becomes much more likely California can get that as well.
It's likely that all of these will be evaluated when the Central Valley test track is built. But I have to believe that past performance will be a factor as well - if, say, the Talgo AVRIL can reliably accomplish its intended speeds in Spain then it would augment a successful test here in California.
Ultimately this decision has political ramifications, and the state of the global HSR market will play a major role. So go have a look at DoDo's post to get better acquainted with that market.