In the sense that Ottawa charges GTAA "rent", yes. But how that rent matches financing charges for future capital heeds, plus past capital expenses that are still being amortized, is another question.
Yes, fed/Ontario governments could build it. Feds have generally had a policy of not subsidizing the largest Canadian airports for many decades. Contributing to a terminal would go against that long-term policy. You have likley noticed above that the money flows the other way, from the airport is a source of revenue to the federal government..
4613 acres with a value of about $1.5M/acre (industrial/commercial zoning) gives Pearson a vacant land value of about $6.9B. Not all of that is actually usable due to wetlands plus roadway allowances if built out so lets say $5B. At $170M/year for the lease that gives them a cap rate of 3.4% which is inline with expectations for commercial property (3% to 3.5%).
So, from an investment point of view of direct revenue only it's good but not exceptionally good. It's in-line with what a private land owner would expect to receive.
Of course, indirect revenue through taxes on GDP growth enabled by Pearson existing are considerable.
Yes, fed/Ontario governments could build it. Feds have generally had a policy of not subsidizing the largest Canadian airports for many decades. Contributing to a terminal would go against that long-term policy. You have likley noticed above that the money flows the other way, from the airport is a source of revenue to the federal government..