Stop sprawl. It's…

Stop sprawl. It's inefficient from a tax revenue perspective ($ per hectare, etc.), it's expensive to service on a per unit basis, it generates endless amounts of automobile congestion and is impossible to develop decent automobile alternatives for (walking/ cycling is too far, density can't support good transit service, etc.).
If the Province is going to use its major powers to force cities to develop a certain way, then mandate that all residential land be up zoned to allow for 6-8 units per lot, and mandate that ultra high density be allowed as-of-right on roads with a right-of-way larger than 40m (not necessarily 40m exactly, but simply allowing high density on major streets by default - cities can then choose to allow additional high density elsewhere, if they so choose).
But the main point is stop sprawl. It's bad and most municipalities are choosing not to sprawl, even though they have the greenfield land available, because they know how bad of a deal it is to current and future tax payers and residents.