You can see this pretty easily by imagining a different 4E, AND no Paizo AND no OGL (and thus little/no OSR, which was significantly enabled by the OGL). Whatever it's form, there would have been a division, period, for sure.
Let's envision a 4E that was incompatible with 3.XE products in the way 3.XE was with 1/2E ones. Very basic design concept changes. However, it's inoffensive in terms of ability design and so on (akin to Essentials, perhaps, but even less risky, with no treasure packages, fixed monsters and so on - the details don't matter). No matter how inoffensive it is, there will be a division. It will be missing stuff some people want, and have stuff some people do not (you and Emerikol are showing this very clearly with 5E!).
Without Paizo, the OSR movement, and the OGL (which is responsible in large part for the former two), that division will be there, but it will be limited. Furthermore, with the lack of an in-print alternative D&D (in the form of PF and OSR games), people who reject it for a year or three will be very likely to try it again after a few years, and may revise their opinion.