That's a fair argument, but in order to keep the railways intact I think metrolinx should buy it outright. Let them sit on it while they expand the regional/provincial bus network.
A side note is my biggest fear is in the future, we will reach a point were we'll need to build new railway corridors, but the bureaucracy will just make it impossible and thus were still stuck with railway lines that only go downtown Toronto when not everyone wants to go downtown.
If we're to fight climate change we need to expand the railway network now, giving people options is the best start, even if ridership is low in the beginning, you can expand it and promote it that will increase its ridership.
Thats my personal opinion.