And before people start commenting on Queen's Quay West or Sumach/Cherry...
It was my understanding why we couldn't do this was because of Rob Ford's underground proposal, and the City's desire to push this through as planned.
@robmausser is right. If we hadn't been so quick to push Line 5 forward to oppose Ford, we could have had a dedicated ROW between YYZ/Renforth/Mount Dennis and whatever Don Mills calls itself...
Not to beat a dead horse, but the South Side-alignment was correct, and we'll be paying for this in decades to come, especially if every other train turns back at Laird.
Look at all the bus routes terminating at Don Valley...
I'll already be punished with a linear transfer at Sheppard (51A/151).