I believe the 4E community is large enough that 5E can't succeed without it, and it doesn't need to be a majority for that to be true. A 4E rejection would compound 5E not being adopted by others, as I don't expect much of the OSR to adopt 5E and due to the fervor of a lot of Pathfinder fans there are going to be significant holdouts there.
If Wizards wanted the 4th edition crowd then they wouldn't even have created Next.
I think you are giving the 4th edition crowd a little too much credit.