Interest in public transit is already plummetting thanks to corona and everybody working from home, and once Biden's National Lockdown in February kills off every last small business that managed to limp through 2020 on outdoor dining and takeout, there will be exactly zero reason whatsoever for trying to move back into the city because once we "build back better" it'll be nothing but chains that are left.
Oh, and woke-inspired policing reforms mean that the cities will be nexuses of crime just like they were in the 1970s and 80s (because you can't enforce the law on any black man, ever, because doing so is literally slavery.) and so once the subways are again the best place to get mugged by a bunch of youths it'll be 1970s/80s NYC all over again where everyone takes Uber and Lyft to avoid getting mugged on the subway and ridership levels (and investment) continue to flatline.
Here's Boston's MBTA, the second most ridden mass transit system in the country (by ridership per mile, that is) slashing rapid transit headways, cutting commuter ferry service entirely, and eliminating weekend service on the commuter rail. Between this and the small businesses apocalypse currently underway in and around Boston, it'll probably take decades for things to recover.
We're not getting national high speed rail, we're getting austerity with a smile.