I think there is a practical limit to 3rd rail speeds - somewhere in the 80-100 range - but more to the point the "main line" of HSR will be electrified with catenary like practically all other HSRs in the world (if they use existing technology). So hanging compatible wire and grade-separating the Peninsula and other terminal portions of the line has to happen, and Caltrain wants it anyway but can't pay for it (enter uncle H$R sugar...).

What I don't understand is why the "terminal" areas have to be full HSR standard or nearly so. Even in France, the TGVs don't always shoot into downtown at 200 mph; they often drop onto "normal" rails at some point and slow down to the speed of "normal" traffic (which Over There is still 80-100 of course, but that's PacSurfliner or at most NECorridor standard not TGV). Also for instance, the Chunnel trains ran on normal rails for years into London (at up to 100 or so, but not full speed) until the money could be found for a new line and rebuilt station; yes, the new line saves time and dispatching complexity, but to start service it wasn't necessary. Since HSR uses standard gauge, you can use normal rails for portions of the route that aren't built to HSR standard yet, or in terminal areas where it doesn't make financial or operational sense to build a whole new railroad. Our CA HSR types don't seem to (or don't want to) understand that.