The 407 Transitway has been on the books for decades, with protections made for it in the right-of-way and at Highway 407 station, so I don't see it as anything new, except perhaps for the section south to Pearson and Renforth Station.
EDIT: Merged the two GGH Transportation Plans
It appears MTO is now thinking about it more as a rail line instead of a BRT corridor, which is what they have completed the EA's for. That's a substantial change.
I agree the document is vague, more of a collection of existing piecemeal plans, with a few big ideas trickled on top (401 widening, Ontario Line loop, 407 rail transit corridor).
The road expansion list is substantial as well, but even it misses several MTO projects they are actively considering and other low hanging items which will be needed by 2051. They show a widening of the QEW through St Catharines for example despite it being widened only a decade or so ago, but don't show the 6-lane stretch getting extended to Niagara Falls, which is very low hanging fruit and will more than likely happen when the Thorold Stone Road bridge is replaced. Same thing with Highway 6 - they show the Morristown bypass but not the highway 5 interchange, a project that has been searching for funding and has a completed EA. the QEW widening through Mississauga for HOVs is also missing, despite multiple projects underway which accomodate it, and they only show Highway 7 being widened to 4 lanes from Donald Cousens to York/Durham Line, instead of fully closing the gap to Brock Road, for some reason.
These documents are supposed to be high level, but the transit front is particularly lacking. It's basically a collection of existing, known projects, with almost nothing added. The document mentions the Bolton GO corridor but doesn't put it on the map for some reason, mentions the London GO extension but doesn't show it on the map, doesn't discuss other potential connections like Brantford, Uxbridge, etc., doesn't introduce any new major LRT routes or any infrastructure above existing plans in Toronto other than the OL Loop, etc.