Pretty much - even the base version of the Mac Pro will take more than half a decade to become obsolete (at the rate we're seeing now). And I believe the Mac Pro's processor is still on a socket (correct me if I'm wrong), so it's also upgradeable.
The new Mac Pro, provided it's socketed, would be on LGA 2011.
You'll probably have an interesting time updating an LGA2011 in 2015, never mind the RAM.