The only place in the country where passenger rail actually has a significant market share is in the northeast. (Well, actually, in the Amtrak 5-year pkan, they noted that the Cascades actually has more market share than the airlines in the Seattle Portland service.) That's all corridor service. Amtrak's vision is apparently to start the work to bring similar type corridor service to other parts of the country.
Rail trips of 50 -500 miles are actually competitive with other transportation modes -- If the shorter trips can be done with point-to-point speeds of 55-60 mph, they can compete with driving, especially in series with heavy traffic. If they have a point-to-point average speed of 80-100 mph, they can compete with flying, at for trips of 200 miles or so, if you factor in all the airport time. The longer runs don't really compete on time, but derive their business from passengers taking trips between intermediate points, just like the long distance trains. If the runs become true long-distance trains, some of this utility is diminished, because there's a ,lot of route for the train to have its schedule disrupted, thus not making it a reliable choice.
The only reason long-distance trains are still funded by the taxpayers is because it's a sop to Members of Congress from rural districts to induce them to support funding for corridor trains serving larger metropolitan areas. You won't believe how provincial our federal system of government is, and that won't change until we amend the Constitution (or have another revolution) and set up at least one house of Congress that is elected on the basis of a nationwide election. Members will support all kinds of things that would surprise even their constituents if they get something more valuable for their districts in return. Why do you think the spending bills are all rolled up into monster "continuing resolutions" that even veteran reports don't have time to really read, let alone voters out in the hinterland? They focus on fights about one big issue, like say the border wall, while, meanwhile, Representative Rural from West Podunk can go under the radar and vote for funding for the NEC and not get turned out at the next election. I mean, he has to be "responsible" and vote to keep the country running, but it also helps if he can say, "well, I got funding to stop the overnight bus bridge on the West Podunk Superduper Chief that they were going to institute."
Long distance trains do have value in our transportation system, but, compared to what corridor trains can do, it's strictly secondary. Unless by some miracle the fiscal heavens open up and deluge Amtrak with cold hard cash, I think all we're going to see is the continuation of the existing long-distance network. If we're really lucky, they might be able to increase frequencies on some of the route s(like the Lake Shore Limited), or build corridors on the back of those existing routes. However, don't expect to see the revival of any classic abandoned long-distance routes any time soon.