Honestly, I feel that highlighted point is up for debate right now, at-least until the playtest is done. They have already done changes I didn't think they would do like moving ASIs to backgrounds, granting Feats to start with and adding levels to them, changing crit rules while implying monsters will get various replaces, etc. I feel it's moving into an area where I think it could be considered a different game. But I don't think your point of view is wrong either.
What I do find strange is that if this is the big document of rule changes, then why not release it with the other smaller packets together? I guess of course that depends oon what the 'big one' means, which I find somewhat vague.
I don't know. I feel that the fact that, if you are correct that this is just 5.2+, then not releasing all the rule-changes and allowing people a guide on simple conversions for content etc. feels even less justified than my understanding of what they're trying to do.