Here is fantasy map for the GTA I drew many years ago:
It's not really about building more rail, but more about integration, all transit in GTA becoming one system, that's the key. The barriers and redundancies are the main thing holding transit in the GTA back, more than anything else.
And I realized recently lack of true regional approach to transit, the lack of regional transit, that is what holding places like Mississauga City Centre, Scarborough City Centre, North York City Centre, etc. from becoming true downtowns. These are still local transit hubs, not regional transit hubs. New office towers still not economical, so these places are dominated by condo towers.
I rode 39 Britannia along Britannia and Matheson in Mississauga yesterday, and bus was PACKED. Even with only 22-25 minute frequency all day, they were already putting articulated buses on this route before the pandemic, and it seems ridership has recovered. Local transit has never been a problem in Mississauga and Brampton and the 905. People living in Mississauga and working in Mississauga, they can ride the bus no problem. Ridership has always been high. It's places along the border with Toronto, or too small systems like Oakville Transit, that struggle. York Region Transit ridership and service 🞵🞵🞵🞵🞵 compared to Mississauga and Brampton Transit, and it's for no reason other than the long border it shares with Toronto. It shouldn't be that way.
Here's another fantasy map I drew to highlight this problem: