AFIK, the 'north Toronto station' does not really exist any more (either as a building that could be used - it is now an LCBO) or with platforms (which were removed decades ago). The rail line is now the main freight line through Toronto (there is now negligible freight traffic passing through the Union Station Rail Corridor.)
I'm sure the effort to turn North Toronto Station into a functioning GO station is not that difficult if that is what the province wanted to do, as compared to new build options in a different location on the line. The greater effort would be the investment required on track infrastructure to remove the contention with freight traffic (i.e. new passenger only rails on the south side of the corridor or a Toronto bypass).
A couple of things to mention here.
The LCBO is occupying the original station, which has been lovingly restored. The restoration was done with an eye to preserving the option of restoring passenger service in the future.
The stairs to the platforms are still intact, preserved behind walls, and covered up top.
from:
https://globalnews.ca/news/1510531/what-you-might-not-know-about-the-summerhill-lcbo/
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Space for the platforms is mostly intact:
Though the LCBO did build into that space somewhat
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Overall, subject to losing one of the great booze barns on earth.........returning the station to active service would be remarkably straight-forward.
As noted by
@EnviroTO , the greater challenge would lie in both obtaining CP's blessing to run the service, and the requisite infrastructure investments (added track, upgraded signalling etc.) that would be required.
However, it's my understanding that CP is in fact open to this idea, provided the province brings the $$$.
I think it's likely it will happen at some point...........but
It's far from a current priority...........I certainly don't expect any investment here in the next decade.
