Nobody here can tell you that definately.
It depends on your definition of revision. Most hardware manufacturers make minor revisions quite frequently that are never announced. The next time you'll probably see a major revision of the MB is when they speed-bump the MBs with new chips. That'll be when the chips are ready, when Intel has delivered enough of them to Apple's facility, and when Apple has enough in stock to meet their expected sales demand.
So, who knows??