Especially if they actually construct or repurpose facilities for pre-clearance.
For existing services, or, more accurately, services that existed prior to the pandemic, the main place that needs preclearance facilities is Montreal.
Vancouver already has them, though they may require a bit of expansion, and has done a "preclearance light" with US Immigration processing but not customs for years. Hopefully that will change with the revisions to the preclearance treaty that went into effect a year or two ago that allows rail the same preclearance rights as air and the border stop at Blaine for US Customs will be eliminated. Getting that agreement cleared the biggest obstacle to doing full preclearance at Vancouver.
The other thing that would improve things is for Canada to exercise its preclearance rights and move CBSA operations into the Niagara Falls, NY station, which is pretty new and was designed with both US CBP and Canadian CBSA preclearance operations in mind. That decision is Canada's and not within the purview of the US Congress.
Toronto is unlikely to get preclearance as the Maple Leaf from Niagara Falls, ON to Toronto is a VIA operated service and serves several intermediate stops. Unless the train were to run sealed to Toronto, international border formalities would still have to be done at Niagara Falls. The main improvement would be for CBSA to do pre-clearance on the New York side using the purpose built facilities there, as mentioned above.
The biggest thing in my mind is reinstating Chicago-Toronto service and I understand the proposal is that it run via Detroit, not the former
International service via Port Huron/Sarnia, which kind of complicates things. It would likely require that Amtrak move their Detroit service back into the former MC station by the tunnel. Luckily, I understand that Ford is at least somewhat open to that. The other is somehow re-jigger the track arrangements/station in Windsor, ON, as there is no direct connection from the international tunnel to the Windsor VIA station. There are operational issues for an international train as well. Both the Maple Leaf and the former International were joint Amtrak/VIA operations due the length of the run in Canada and the presence of intermediate stops, as opposed to the relatively short Canadian runs of the exclusively Amtrak operations into Vancouver and Montreal. I seriously doubt that the Canadian government, Canadian Unions, or VIA itself would allow Amtrak to operate such a long service in Canada. So VIA's cooperation is essential in starting such a service. And I understand that even the continued VIA operation of the Maple Leaf may be in at least some doubt post-pandemic, with Metrolinx now offering multiple rail frequencies Toronto-Niagara Falls. As an aside, both the Cascades and the Adirondack are back in Arrow and bookable starting early in 2022. The Maple Leaf is not.
Honestly, the money pit here is restoring Chicago-Toronto, as are most of the issues that would require study. I would expect most of the funds to flow that direction.
