Yeah, I pretty much knew that, but Congres and the White House should start moving on changing the law. Transit funds are short nationally, and a change in the law along these lines would serve well the construction of transit routes in a lot of metro areas.
Even assuming for the sake of argument that a policy change along these lines is a good idea, the time to attempt it was two years ago, not now, because right now there's zero chance of it happening. Not when you have an incoming GOP majority in the House that's still reflexively anti-tax, usually anti-transit, and with a big strain of political-ideological disdain for (blue-leaning) metro areas and a concomitant desire to 'punish' the same. Not to mention the fact the (substantially more bipartisan) Congressional tendency to heavily preference road vehicles over transit (which, to be fair, does tend to reflect a good chunk of the views of many constituencies). I don't know to what extent the administration could effect changes without legislative action, and even if there's some room for them to do so, I wouldn't expect to see much on account of that being where things get messy (stretching the definitions of what laws permit is one thing, i.e. when Massport has to haggle with the feds about what they can use the airport dollars on in terms of transit service to Logan, but wholesale policy changes tend to be where the courts get ornery about the White House doing Congress's job...and where the smarter administrations accordingly tread carefully.)
As a sidebar, I'm not entirely certain I agree that it's necessarily a good change to be made, at least from the federal perspective. Allowing states a lot of leeway to put up tolls on interstates opens up a lot of currently-unavailable wiggle room for shenanigans, as well as imposing direct economic costs on users. You can limit shenanigans if the feds say "you can put tolls, but can't exempt or discount in-state users", which would keep, say, Maine and NH from mooching off MA vacationers, or keep New York from socking it to commuters from NJ and CT (though they already manage that fine with the MTA and the Port Authority, some would say). Problem with that is that it screws anyone
in your state who regularly uses the road you've now slapped big extra costs on. If the federal perspective is that the interstate highways are supposed to be (notionally, anyway) facilitators of interstate commerce, allowing the states to toll them for their own purposes kind of goes against that basic federal purpose. It wouldn't necessarily be a bad idea if a federal policy was "we're going to
federally toll the interstates, to fund additional transit priorities and encourage more-efficient transportation methods", but that would require that the feds a.) decide to do that (see the political quandary discussed above) and b.) didn't appropriate the funds for other pet projects (and this is
Congress we're talking about).
On the other hand, if we move away from the federal entanglements that make dealing with the interstates a problem, it's certainly a very interesting idea to discuss the idea of tolling some of our own state (and local) routes as a proto-road pricing endeavor (or, you know, full-on road pricing wherever Washington's preemptions don't make doing so legally dubious absent "cue the flying pigs"-level Congressional action) and mandatory-linking that to transit funding. Might be more successful than the ill-fated attempt to fund transportation priorities with a gas tax increase, especially if it's planned out well (i.e. you don't clog every street from Leverett Circle to Kenmore because you set the price too high on Storrow), something that goes double if you limit it to specific arteries (and therefore can dodge the worst of the surveillance concerns).