Wouldn't the Bloor/Danforth extension component alone be many billions of dollars? That alone doesn't seem feasible. Like Tiger I also laughed when I realized the Sheppard Extensions were just one stop each, but that could make sense if you could add stops later. I wouldn't consider it a priority though. I have no idea why they're even considering putting a Scarborough B/D extension underground - it's going to cost a premium. Why not just keep it above ground like other sections of the subway?