I was looking at pictures of Michigan Central Station, Buffalo Union Terminal, Cleveland Union Terminal, Cincinnati Union Terminal, and other derelict stations earlier today (I know Cincinnati isn't actually derelict, but it only sees six trains per week in the middle of the night). Suddenly, out of nowhere, a question struck me. How expensive is it/was it to operate large terminals such as these? Obviously lots of airports and large passenger train terminals function as more than simply travel endpoints, since they also can include retail and office space. It seems like this would particularly apply in the case of Detroit, Buffalo, and Cleveland, since they all have a great deal of square footage that isn't train-related. My intention is not to question whether Amtrak should have hung onto or acquired such facilities (that would belong "next door") but rather to ask this: Does the ability to lease space to retail, offices, and others defray the cost of operating large stations (in North America and elsewhere), or are large, dedicated terminals always costly to own and operate no matter what's in them or how many passengers pass through them?
Search online for the proposal for Washington Union Station in the District. The station already has substantial retail and food vending tenants. This huge project would add buildings to the complex.
I would expect that cost of energy and upkeep for a large station is substantial, and that retail space rentals helps to offset that cost. So long as any variable costs of allowing the rental is more than recovered, a portion of fixed costs is offset so the railroad or airport operator is better off.