You can't upload without uploading all the transit services. But that is a massively expensive proposition. On the other hand, profitable subways are seeing those profits go towards subsidizing feeder bus services instead of upgrades (like platform screen doors) or expansion. And from a political and regional perspective, the province has massively contributed to the capital costs of the subway network only to have the city view the subway network as their own, which in turns plays into the debates about regional utility of that network (like what we see on Yonge North) and even issues like regional fare structures (fighting fare by distance...).
I can easily see the province uploading the subway and LRT network to Metrolinx and leaving the feeder bus service in Toronto's hands with some compensatory subsidy. The subway then becomes a regional asset where regional ridership and regional development goals are considered. Would think suck for Toronto? Probably. But from a regional perspective? Definitely not.
I just don't like the idea of picking and choosing which parts of a network you want to assume control of, and leaving the other guy to pick up the tab for the rest of it. Uploading the whole TTC may actually be less expensive than just uploading the RT network, because of all of the employee splits that would need to go along with it. If someone spends 50% of their time doing planning work for the RT network and 50% of their time for the local network, do they stay a TTC employee or do they become a Metrolinx employee? Uploading the whole thing in 1 go allows for a wholesale merger.
does your "all" mean all buses and RTs?
Buses, streetcars, RT, everything.