Grainger
Explorer
We will see what happens but I will bet you that if the schedule doesn't increase then D&D will suffer.
We'll never know, though. If 5e fails, you could draw the conclusion it was because they didn't release enough books. But it might be that they released too many books, or perhaps it was a bunch of other factors.
Conversely, if they release a ton of books and then 5e does well, you could conclude this was because they released lots of books - but it might have done even better if they had released far fewer.
Time isn't going to make us any wiser about this than we are now, and even when judging whether 5e is a success, what players think might be different from what Wizards does.