Mazda Australia is reporting that a 2.5L engine will be added as an option on AWD models. It will be available in the 1st quarter 2013. NA will be close behind. Here's the link.
http://www.theautochannel.com/news/2012/11/19/057338-mazda-cx-5-adds-powerful-new-2-5l-petrol-engine.html