Bereft as I am of a working crystal ball I cannot lay much on my own predictions here, right? Okay.
My guess is that it won't be so much a split as a lag in people adopting the new books. As folks set in their ways often do, we'll grouse and insist the 5e books are largely fine as they are and didn't need all these changes, but as more and more people take up the new system, most of us crusty old curmudgeons will come around to the new books and settle in to using them. There will, of course, be a few who insist on sticking with the prior system (that always happens, too), but I expect by and large it won't be a big deal.
It isn't fifth edition that so many people have fallen in love with over the past four or five years; it's D&D.