The freight rails are slow and dilapidated. It would make more sense for passenger railways to be separated from freight railways entirely rather than to try and squeeze into inadequate trackage. We don’t try to unload air freight through passenger terminals or vice versa.
The I-5 coast and everything west of I-35 represents most of the US population. In particular, Chicago, Atlanta, and New York form a triangle roughly 700 miles on each side. This is roughly the distance between Beijing and Shanghai, or Tokyo to Fukuoka, both of which see high speed trains regularly making the full journey.
No, I can't, but I don't have to imagine the insurmountable resistance when the government merely suggests using eminent domain on a rich person's property.
Besides, poor people don't own property in the US anymore.