With most of the line being in streets, it won't be a fast ride. Of course, they do need some way to gather/distribute riders from the tunnel under Sepulveda Pass. Connecting Metrolink and Amtrak in the Valley is hardly a significant proposition, though.

IMO, a good Valley rail transit deal would include extending the Red Line from N Hollywood to Burbank Airport (the airport itself, plus maybe the HSR station), and a connection from the airport to Pasadena Gold Line. At the moment, if you fly into Burbank (which is the best airport for access to downtown LA) but want to go to the SGV, you have to ride Metrolink downtown then the Gold Line back out, or take the occasional local bus from N Hollywood Metro (there's a shuttle from the airport) that trundles by back streets (often within sight of the freeway, but never on it) over the hill to Pasadena. The longer (to and from downtown LA) trip is actually shorter in time, but neither even remotely competes with Uber or having somebody pick you up. Or even renting a car and driving, including the 1/2 hour or more to get to the off-airport rental site and do the paperwork. Ultimate alternative is fly into Ontario and rent a car (no other practical option there).