Yes, there is - the 2051 GGH plan is a doc that came out about a year ago from the MTO/IO (not Metrolinx- the next RTP will tell us how much of this is “real” I suspect). It indicates exactly what your talking about- OL from Science Center to Don Mills, looping West via the 407 and down again to Pearson and then Kipling. It’s interlined with the (much more interesting imo) “interegional LRT” from Burlington to Oshawa, which is effectively a revised rail version of the 407 Transitway that follows the Mississauga busway via the 403 to Pearson instead of through Brampton.That was kind of my point. I was responding to mossynukes who said the plan is to go through Humber Bay Shores - and I've not see any plan that shows that!
Is there a 2051 map?
In terms of actually getting built, I think the OL section between Pearson and Vaughan might be even more speculative. Or perhaps the piece between Richmond Hill and Don Mills.
As for what’s most/least viable, I’ll agree that your latter option- RH to Don Mills- is one of the weaker points. If anything, MCC-YYZ (followed by YYZ-VMC/YYZ-Kipling) is the strongest section of the bunch, and IMO should be prioritized as an independent line to start us off at some point soon if we want to actually build a massive 100km+ line this century. Obviously the issue is there are so many other things worth getting done first.