The California High Speed Rail Authority (CHSRA) is meeting federal requirements for “independent utility” with a plan to have Amtrak trains use the Central Valley tracks, if and only if, the rest of the high speed rail project is not built.
Some potential issues with this plan:
1) Someone will have to be responsible for track maintenance costs and right now there are no volunteers.
2) There is a large incremental cost ($100-400 million) to make rail structures strong enough to support the trains Amtrak currently uses.
3) Rail structures that can support heavy Amtrak trains are bulky and more obtrusive.