Tacking a separate question on for anyone who's read this far: It looks like there's already a Union Pacific rail line from LA to SF, via Santa Barbara and hits

Tacking a separate question on for anyone who's read this far: It looks like there's already a Union Pacific rail line from LA to SF, via Santa Barbara and hits Monterey/Santa Cruz along the way with some scenic ocean views. What would it have cost to simply upgrade this line to be able to handle some passenger train traffic at normal speeds, like Amtrak does already? Wouldn't that be online by now?