As a European it boggles my mind seeing how trains are basically non-existent in the USA (just look at Houston station), given how dominant the whole "Wild West" railroad rush is in everybody's immagination. Railroads are super ubiquitous here, and we've to work with a pretty hostile terrain - Italy has lots of mountains, hills, rivers, and yet has one of the best networks in the world. Most of the USA are basically…
In Europe with we have spoke-and-hub railways - want to get into London? There's almost certainly a local station near you in the suburbs. Then jump on the Eurostar to Paris. Get to Paris, and then get a local line back out to wherever you want to go.
Right now, it would have to be airport like terminals, and a multi-decade (if not century long) plan to connect the city centres.
In the US, drive to the new high speed mainline station outside the city, where there would have to be as much parking as an airport, and then get the high speed line to the destination, and then... hire a car?
Building a mainline station in many US city centres for high speed lines isn't going to work right now. There are too few local lines going in, and nowhere to build super-sized car parks.