They originally said they intended for this tour to last until summer 2013. With that said, this is my prediction for how the rest of this tour will look.
April-September 2012- North America/Europe, which we already know.
November/December 2012- Australia (confirmed to be happening. probably also dates in New Zealand, Japan, and maybe other southeast asian countries)
January/February/March 2013- North American arenas, then head to south to Mexico, then heading further south into.....
March/April 2013- Latin America leg, confirmed by band members to be happening in March/April
Early summer 2013- More European dates, stadium or arena, who knows?