I think the naming is an attempt to distinguish the Surface Pro from Surface RT in order to address some of the customer confusion about capabilities ('this device runs Windows 8 Pro"). But I would expect that for those customers, knowing Pro vs. RT doesn't really help any in answering their questions. The naming also creates a very awkward problem for dealing with later versions of the OS. Just taking the number out of the name -- i.e. Surface Windows Pro instead of Surface Windows 8 Pro would be better. But at that point, you should just drop the Windows too and go right back to the SurfaceRT and Surface Pro we had before. MS has been using "Windows 8" as a brand, most likely to emphasize the departure from previous versions. But highlighting the change from older versions makes it more awkward for future versions.
Microsoft has always had the worst product naming of any company in the history of time. Most of the products would be much better off to stick with the internal development names.