I could see the Argos moving to a purpose built stadium in Mississauga or Vaughn or Markham.
The issue with grass at the Dome is light - that darn photosynthesis thing. Science has yet to work out how to do a field that big with our weather; the only examples are in warm weather where a dome can stay open most of the year. Rogers talks about it but I suspect it will be another 10-15 years until they do. By then, they should be thinking of moving to a purpose built stadium north of the city as well (Downsview comes to mind). The Dome isn't designed for a 50+ lifespan.