Any sort of train system will not make economic sense until we densify the end points well past single family homes with some scattered townhouses.
Even Westhills isn't dense enough to economically support a train system, and there's nothing else on the route that even comes close to that.
I honestly think our best path forward is to just wait for electric autonomous busses rather than try to build light rail.
The limiting factor (both for capacity and cost) on the bus system right now is drivers, operating a bus 24/7 for a two years costs costs more in driver wages than buying a fully electric bus and prices are dropping rapidly on those. The fuel costs also drop absolutely massively with the switch to electric, on the order of 80-90% cost reduction. Given that the busses will last for decades, you can see how much cheaper a driverless electric bus will end up being over it's life allowing us to buy far more (More routes, more frequency) for the same money we're currently spending and run them for a greater portion of each day (downtime for charging and maintenance) so you could easily have night service if there was a even a hint of demand.