I have no doubt that the sincere, good designers on board and working on 5E are fully capable of making a really good or even great game, though I wonder how good of a roleplaying game it will be. If it turns out to be a great roleplaying game and released under the OGL, I will likely be playing it, running it, and supporting it as a 3PP. If it is only a passable roleplaying game and under the OGL, I will likely play it a few times (without actually making a purchase, or maybe just a PH) and will not likely support it. If it is a good/great roleplaying game but not under the OGL, I will likely play it a bit with or without purchasing a PH and, obviously, not be a 3PP (not even with a restrictive GSL). My reasoning is that there are plenty of other games to support that are OGL released and if I am supporting them I'll also want to primarily be playing them. It won't be anything personal against the designers, the brand, or even WotC as a business, except of course that I won't care for the fact that they didn't learn enough from the GSL debacle to revert back to OGL support. We'll see.
However, there are plenty of reasons why some folks are saying that they have no interest in 5E, even prior to the announcement, and WotC has made it clear that they want to hear from all D&D players, all RPGers, even if what they are going to hear are the reasons someone has no interest in 5E. Acting as if vocalizing that position is somehow wrong is precisely what WotC doesn't want its diehard supporters to quash. It is information they need to know and supporters who try and stymie those who wish to voice such opinions aren't helping WotC, D&D 5E, or the gaming community by creating an atmosphere where such opinons are not valid or easily expressed.