The present incumbent national leader wants to slice Amtrak funding by half. But most think that 'Amtrak Joe' would most likely be Pro-Amtrak... although nothing is for certain. We can only hope for a full restoration of Amtrak post pandemic, although LD is really taking a hit. Wish we could crawl into the Amtrak part of Joe's mind. He definitely is an 'Amtrak kind of a guy.' Hmmm... so much to wonder about; safe to say next year at this time we will have gone through some big changes.
If we have a new President in January, I suspect that there will be a lot of issues with a higher priority than the details of Amtrak service. In any event, the President doesn't really have all that much authority over Amtrak. As you pointed out, the current President wanted to cut Amtrak funding by half, but that went nowhere with Congress. And that was a Congress hostile to government spending and of the same political party as the President.
That said, Mr. Biden and his political party are, indeed, more supportive of funding for rail transit than the other side of the aisle. Furthermore, they're more likely to be concerned about reducing greenhouse gas emissions and other emissions of air pollutants. Thus, they will tend to be more sympathetic to funding passenger rail and public transit as a tool to help get people out of their cars. But this means that they will probably want to focus on improving and expanding short-haul corridor service that has the most potential to significantly reduce the automobile vehicle miles driven. Long-haul service is secondary, but everybody agrees that it should be supported to provide mobility alternatives for rural areas, especially those not served by other forms of public transportation. This also provides the national political support for all passenger rail.
However, most passengers, even on long distance trains only travel relatively short distances. Thus, catering to passengers traveling the really long distances is probably the lowest priority for funding. There are still good reasons to do so: There's a small, but significant percentage of the population who can't or won't fly or drive, often for medical reasons. In addition, the premium services catering to long-distance passengers (sleeper and business class) have a revenue yield per mile that's almost twice that of coach. Thus, the gravy pulled in by the customers of the premium service helps cross-subsidize the long-distance service for coach passengers. This, by the way, is a good reason for Amtrak not to outsource the premium services, as if they are outsourced, the private operator would be getting that gravy, not Amtrak.
In summary, any new administration, especially if there's a change in control of the Senate, will be more friendly to funding passenger rail than we've seen in a long time, but don't expect any miracles with respect for improvements in service on the long-distance routes. What I'd like to see is policymakers and political leaders start taking passenger rail seriously as a viable transportation mode for the masses across the country, like it is in the Northeast.