Chinook Centre in Calgary is that city's Yorkdale. It's the most logical place, even more logical than downtown (which is the only other potential site for a high-end retailer).
Rideau Centre is doing well, not spectacular, but well. I'm sure CF will easily find new tenants to replace the Sears. Ottawa is a really strange place when it comes to malls, I would suggest it has too many regional malls competing with each other - Bayshore, Rideau, St-Laurent, Place D'Orleans plus the various local malls and big box centres everywhere and this only counts the 750,000/800,000-strong Ontario side of the Ottawa River metro.