I talked to a Mazda salesperson recently who said that the 5 SHOULD be redesigned for 2011, OR replaced by another car not necessarily labeled Mazda5. I asked him if the CX-5 was indeed coming to Canada then and he said he just didn't know and Mazda wasn't telling.
Thing is the 5, despite it's strong sales, is still not a real poster-car for Mazda. Consequently the press won't be itching to find prototypes in camo out testing in the extremities like they would for say a next-gen RX car, MX-5, or Mazda3.
Corporate Mazda, knowing this, won't be exactly eager to release 'gripping' new info on the upcoming redesign/replacement either. I don't expect to see it at any major auto-shows, or press-conferences prior to the showroom. Maybe we'll just see brochures, and a couple of official photos a few weeks before release. I'm guessing you'll see those pictures in August of 2010.
The sales guy said nothing about the replacement car specifically but agreed with me that it would have traction/stability, Mazda3 -ish design language, the 2.5L engine, and a little more interior refinement (also like the new 3).