There had been rumors that Wrestlemania 22 would be headed to Calgary for the Saddledome, and outdoor stadium that seats about 45,000 people.
However, it appears that it is not likely that the event will be held there for a number of reasons. First, it is a very large venue for an area that only drew 10,974 paid for Canadian Stampede in 1997. Also, Vince McMahon is not a fan of running outdoor venues and risking a weather problem, especially in Canada in late March/early April.
The return of Bret Hart at such an event would likely be a huge story in Canada, but it could conceivably be held in many Canadian venues and still be a major event.
credit: Dave Meltzer Wrestling Observer Newsletter