The transit won't get built if it doesn't make economic sense to do so, and right now it doesn't make sense to do so because most communities aren't dense enough to support it. Fix the zoning first and allow dense construction, and then it will become economical to build out transit. No one's going to build subway out to single family home suburbs; it will simply never be economical. About the only thing that makes sense there is bus routes (which already exist). But building subway to a neighborhood that consists of 5 floor multi-family homes and mixed street level retail? Yeah, that works. That's what large swaths of NYC look like, and land value here is higher because of it (which should appeal to existing owners).