If you're looking for a definite answer before Beta even starts, You're going to be sorely disappointed, they've already said that that decision is entirely based on feedback they receive during testing/6.0 going Live. That's all there is to it, if the majority fly into an uncontrolled frenzy, yeah, we'll probably see it restored (not that I am advocating this behavior), but if it remains limited to a vocal minority (which it currently is, no matter how you spin it), we probably won't see it returned, as no flying is generally much healthier for open world gameplay.