You guys want two downtown tunnels?
I'm down.
Most of the maps I've created recently show a SmartTrack DRL under King-Wellington-Front (King in the west, Wellington through the CBD, Front in the east), and a Queen LRT. The LRT would run in a dedicated ROW from Roncesvalles to John, then dive into a tunnel through the CBD (facilitating easier connections with Osgoode and Queen Stations), and a dedicated ROW again from Church to River.
In this scenario, King would become the long haul transit route as well as the vehicular surface route, while Queen would become a surface transit and pedestrian street, catering to more local travel patterns.
So in essence, it would kind of be 2 tunnels in downtown, just the 2nd one would be a lot shorter.