In order for the Sunset to be rerouted off of one line to another, 180 days notice would have to be posted for any stations losing service. While I'm sure Amtrak has considered rerouting the train, I doubt any decision has been made, or that consideration has ever even gone beyond the "what if" level (save that one time a few years ago with Warrington's Marked-Based Network Analysis plan).
Some would even say that Amtrak doesn't care enough about long-distance trains to make such a reroute even worth its while. *I* wouldn't say that, mind you, but some would.