I could see Toronto and Vancouver in the NFL some day. Probably before we see Ottawa back in the CFL. [/quote]
The CFL will be around for a long time. Toronto may leave, but in Western Canada the CFL is THE football league. Yes people follow the NFL, but here the CFL is king.
As far as expansion goes, the only city with a stadium close to CFL sized is Quebec City. With the implosion of the one set of stands, even Ottawa no longer has a stadium big enough. That said the stadium will be rebuilt in time for Ottawa to kickoff for 2010. So there's one new team.
But hypothetically, after Ottawa, the next best candidates are Quebec City and Halifax. Once you go beyond them, there are no other cities that even come close to having CFL ready stadium. Saskatoon is probably the only one in the West that with a ton of renos could come close. Griffiths Stadium on the U of S campus was expanded to just under 13,000 for the Vanier Cup. If they tore down the West Side stands, there is room for stands to seat maybe 10,000. So with a lot of work they could hit 20,000 seats.
Let's say hypothetically, the CFL wanted to move back into the US, the $1,000,000 question is can these stadiums fit a CFL sized field? I can't remember where I read it, but Commissioner Cohon had said that if the CFL were to ever consider moving back to the US, one of the conditions would be the stadium would have to be able to fit a CFL sized field. I'm not sure that there are any stadiums in the US that would be able to do that. Most soccer fields are wide enough, but not quite long enough for the field (which is the problem with the Argos moving to BMO Field).