I don't HATE the Scarborough plan but I think an LRT was more sensible and even if the subway makes more sense, every aspect of the process was corrupted by petty politics. More development along the streetscape (i.e. LRT) makes more sense than trying to stimulate the very localized intensification that hasn't happened with decades of planning to that effect. The bigger problem isn't the subway itself as much as the process and then also the idea that it queue-jumped the DRL and Yonge extension, both of which are more important.
One of the great ongoing jokes on this thread is the clash between people who think it will overwhelm the system on Day One and people who think it's going to nowhere and therefore will be a drain on the system. Can't have it both ways. It will be a stress on Yonge-Bloor, no doubt. But if the ATO comes online, and the Spadina line, and the bigger trains, it should be good enough as long as the DRL is planned to come online not too long after (i.e. before all the new development).
Hypothetical? You mean like this nearly-complete development at Yonge/Steeles?
http://www.libertydevelopment.ca/worldonyonge/
The zoning is in place. The developers worked on and agreed to the plan. The only "hypothetical" element is the subway (and, yes, other transit infrastructure like the transitway and expanded GO). If they announce it tomorrow, the sales offices will be open before New Year's. Obviously Metrus isn't going to give up it's golden leases on the north side of Highway 7 before that but the Markham half is totally ready to go. As for the hydro corridor...well, if you don't know what the development plans are for the node itself, plus the new zoning along Steeles (in Vaughan and Markham) look back on this thread.
I don't think that's obvious at all. When's the last time you were at Yonge and Steeles? There is already more development on the Markham side than Toronto. Markham and Vaughan have updated, high-density secondary plans for Yonge Street now in place. Toronto hasn't even started such a process as far as I know. The Highway 7 area has been a designated node for several years and those plans, as I just said, are also in place. Developers don't decide to build transit-oriented development on Yonge Street on a lark. It will happen as surely as North York Centre did. But, as I've also said before, I'm sure there were people, circa 1970, who didn't want the subway to up to Finch based on "hypothetical development" in the middle of nowhere.