I strongly suspect that we will see a Phase 1 + Phase 2 Ontario Line project, likely due to costs or political realities. I suspect the south-of-Danforth segment to be completed first, in line with DoFo's Ontario Place plans.
Agreed about the phases, for a number of reasons, not least to 'show' to investors. At least it will be 'planned in part', and I think that will just be a version of the City/TTC Pape to Osgoode segment.
There's real advantage to adopting as much as possible of the TTC's early planning, especially as that relates to EA. (edit to add: )
it is starting brand new ones that the city and province is bananas at.
Absolutely!
Where I think QP should vary is in the train tech used. Not orthodox subway, or metro, but the latest now being adopted in London and some other cities. The grunt work has already been done, and it can use the 5.4m tunnels the TTC has planned, (Great Northern Class 717 as described prior are running in 4.9m tunnels, so QP can press ahead on that, and even though the platforms will be too short, as
@BurlOak has stated and others, only open the doors necessary for shorter platforms. It will require longer platforms at major interchanges however, or at least provision for lengthening them.)
QP's real enemy for their clumsy sales attempt is time. And pressing ahead on the DRL as TTC/City planned + would be the sane way to go, save for building it standard gauge to allow GO RER vehicle use as London/Paris et all are doing with hybrid Class 700 series type trains. Bombardier is building very close copies with their Class 345 for Crossrail. The 700 series are specific though in being hybrid running on both third rail and mainline catenary.
The only engineering challenge really is for a maintenance yard for these vehicles, and since ramps at Pape to Line 2 won't be built, returning to the original plan for ramps at Gerrard would make sense to allow shuttling along the Lakeshore Line to a yard at the foot of the Don now underutilized by GO. If QP insists on the bizarre scheme of a bridge at Eastern, that could also serve as a connecting point to a yard just south of there.
Once this line is ready to be proceed, then investors can be invited to bid, and phase 2 will be to extend either or both ends.