Firstly, I'm all for opening up the yellowbelt. But I'm not sure why these things are mutually exclusive.
This has literally been in the Growth Plan since 2006. They made a greenbelt and drew a line around the GTA and said, "You will intensify, within these lines."
Then they made 25 little dots and said, "But here, you will REALLY intensify."
And we always knew this would be one of the "really, really"s, because of the transit convergence and the virtual blank slate presented by the current uses (both here and in Langstaff Gateway).
And that's what they're doing, finally. It's not remotely news that there would be big towers at this exact site, nor is it news that the Richvale neighbourhood to the west isn't going anywhere any time soon. Royal Orchard and historic Thornhill aren't going anywhere soon either, but as I said above, you will be getting very significant density along the Yonge corridor, along its entire 401-Major Mac length. From Steeles to the growth centre alone, you're talking about something like 100,000 residents. The Growth Centre itself is supposed to be like its own little city (well, 2 of them, kinda), by design. Always has been.
We should also be loosening zoning etc. etc. but it's really a separate argument (and one triggered by, I mean, a massing model that's not designed to show the development in its future context, or it would also show Langstaff - but all those towers in one graphic would REALLY scare people) so I really don't understand the surprise or scepticism about the execution of a plan we've been watching for 15 years now. If someone showed you this in 1995 and said, "That's Richmond Hill," you'd laugh at them. "80 storeys in Richmond Hill? Sure! Sure!" I've spent most of that time on the YNSE forum, arguing the entire point of the subway was to facilitate this level of intensification; something RER could never do.
Now somehow it's unhealthy?