I think you should wait till 2015 because the Macbooks then will have the performance on today's Mac Pro's in a mobile body... *tsk tsk
Seriously though, if you want to buy a Mac go buy it. If you don't need it right now... wait till whenever they decide to update their products... until the specs meet your preference... No one can give u a definitive date of when they will be refreshed, cuz only The Jobs knows and he doesn't even spill the beans even to his wife.