I totally agree with this. There's a few things I'd like to nitpick though, if you don't mind
First of all, the entire Downsview area, I can see getting development. Lots of it. If you look at Sheppard and Allen right now, you might find that there's a lot of development going on currently. That said, I can never see Jane and Steeles-407 getting anything. Ever. There's just nothing going for it, even if there was a gold plated subway to downtown.
Which brings me to #2: VCC. As far as any belief that VCC (or VMC, whatever you,) will be an utter failure due to Vaughan's past growth strategy, I don't think so. It's not like people in Vaughan are going to be moving to VCC; it's supposed to be a high density downtown-like district, complete with condos and office towers. I think that definitely needs subway. But plans haven't been finalized yet, I'm not even sure if they have the developers up, and work definitely isn't going to start for 3 years. That means nothing's going to be finished for at least 5, and probably nothing notable for 10. I absolutely agree that the York U-VCC extension should be put on hold (Steeles West included) until we can get a definite timeframe on VCC. That still allows Viva Purple to have a solid route (currently it goes to York U, so it could go to York U and come back up Orange's route,) and it provides the needed service to York U.
3rd, I'm not so sure about (ever) reaching Canada's Wonderland, but the area definitely needs to mature before subway hits it. Maybe 50 years down the road, the current Jane suburban office park stretch will turn into a solid 10 story row of midrise offices, then a subway could make sense. I doubt it, and it's definitely not what I'd like for the region. And even if, the Jane LRT would probably be better for shuttling people to VCC and the Subway and Viva. Actually, by the time that warrants a subway, we'll already have a Jane-McCowan subway on Highway 7