Also, and I beg you to pardon my ignorance... but what exactly would be CP and CN's business case against leasing, or transferring, the ROW to a publicly-subsidized agency? From a commercial and practical point of view, nothing would change except the fact that engineers would have to call a "foreign" RTC. Also, the "loss" of ROW property would mean reducing operative costs, and everybody knows that infrastructure costs are among the biggest red figures in the bill at the end of the year.
According to a RAC report, in 2018, Canada's railways spent a combined 2.38 billion CA$ for the maintenance of its 49 422 km network (~ 48 160 CA$/km).
To make a comparison, the AAR estimated, for the same year, an expenditure of roughly 29 billion CA$ for the maintenance of the 225 000 km American network (~ 129 000 CA$/km), while Rete Ferroviaria Italiana (RFI), subsidiary of the state-owned holding company Ferrovie dello Stato (FS), spent 6.5 billion CA$ for the maintenance of the 16 781 km railway network (~ 387 400 CA$/km). (The Italian figures shouldn't be surprising, considering that more than 70% of the network is electrified and 45% of it is double-track.)
Now, taking into account a core-network of roughly 2 103 km of Corridor lines, we could make three expenditure hypothesis: the first, with RAC costs/km, would see an annual government subsidy of 101.3 million CA$/year; the second, with ARR costs/km, would see an annual government subsidy of 271.3 million CA$/year; and the third, with the Italian ones, a subsidy of 814.7 million CA$/year.
Except for the Italian-scenario subsidy, which is clearly unrealistic considering the aforementioned characteristics of the Italian railway network, a publicly-owned Corridor infrastructure wouldn't really shake the economic stability of the government.