Seems like the end points don't dictate the Coast Starlight's schedule: Sacramento does. It is the begin or end point for a huge number of trips. And the current times at the capital city are excellent.
Agreed that the higher priority is to make the Sunset Ltd daily, that change just might entail a schedule change as well. The potential effect on the Starlight is imponderable now. The current arrival, btw, seems terribly early, looking at clocks set on Pacific Time. But the Time Zone change means that passengers' bodies feel like they got an hour more sleep than the clock says, and that's good.
Meanwhile, in a 10- to 20-year time frame, the route will change underneath the Starlight.
More minutes will be shaved off the run Seattle-Portland when, not if, but when, the Cascades route is further upgraded. Still more minutes will disappear when Oregon upgrades its Cascades routing Portland-Eugene.
California could do more, and get it done sooner. The northern segment of the Pacific Surfliner route, L.A.-San Luis Obispo, will shed minutes as curves are straightened etc over a multi-year upgrading. Another chunk of time will drop out with the revival of the Coast Daylight or whatever the second thru train L.A.-Santa Barbara-San Luis Obispo-San Jose train will be called. (Those tracks north of S.L.O. up to San Jose have a lot of potential for improvement. LOL.) And also on the to-do list is upgrading the Sacramento-Redding corridor, making those 150 miles or so go a little faster for the Starlight as well as the corridor trains coming there.
So I'm not going to try to change the current schedule. I'll lay back and watch infrastructure investments change it, and change it very much for the better. In that 10- to 20-year time frame, the Coast Starlight should grow and thrive. It will be another example that the cure for what ails Amtrak is more Amtrak.