They've literally already changed things in the playtest according to feedback. In D&DNext's Playtest, the feedback they got shaped the 5e we got in 2014. I see no reason to come up with baseless conspiracy theories about how WotC is pretending to "playtest" these things among the community but will ignore them and do whatever they want.Yep. I have a feeling that the playtest will last 12-18 months, then it will be closed and WotC will do whatever they want regardless of feedback.
Have you not looked over any of the playtest documents yet? There are some pretty major changes being tested out (Class Groups, Feats becoming core, Half-Casters getting cantrips and spells at level 1, new crit and inspiration rules, etc).If OneD&D is just fixes and tweaks to a half version from 5E to "5.5E" why even bother having a playtest? My bet is that we will see an entirely new edition based on the d20 chassis of 3,x and 5E, but thats just my opinion.