I still cannot see this happening, for all of the reasons mentioned above. TFC will be hard pressed to fill a 30 000 to 35 000 seat stadium and the Argos would likely be cramped in a 25 000 to 30 000 seat stadium. TFC supporters have been very vocal about NOT allowing the Argos to move into BMO (note that unlike the NFL the CFL's schedule parallels much of the MLS schedule which would create scheduling conflicts which don't exist for the NE Revolution/NE Patriots the only teams I can think of that share a stadium).Also the Argos would rather be the main tenants or operator of any stadium they move to rather than being second fiddle.
Unfortunately it seems that too many pieces of the puzzle fall nicely into place in this plan that it seems all to likely to happen: The argos get an outdoor football stadium. TFC gets a much needed stadium renovation. The Blue Jays get natural grass in the dome (this could likely extend the life of Skydome by at least 10 -15 yrs before Rogers decides to tear it down). MLSE gets a venue for an outdoor winter classic. So I am skeptical, though I'll believe it when I see it.
Tim Liewiekie has been pretty aggressive since taking over MLSE, they have gotten the NBA All Star game (though not so much the work Tim did but his predecessors). He has spoken about an NFL franchise in Toronto. He has mentioned the NHL All Star Game and Draft, and now the Winter classic. All which seem to be culminating with the team's centennial in 2017.