This is about what I thought they'd try. A couple of boxed texts as a "conversion document" is pretty mild.
Sure. But there were several people who argued that making feats non-optional was totally breaking any semblance of backwards compatibility. Or that they couldn't make any significant changes to classes, for the same reason.
This document pretty conclusively proves that, at the very least, "completely backwards compatible" does not mean "only minor/cosmetic changes or rearrangements of existing effects." This is a legit top-to-bottom re-evaluation. The fundamental underlying math isn't going to change (sadly), but their approach to how it works may do so.
That Healer feat, for example, actually looks almost kinda-sorta serviceable as a legit replacement for Cleric healing. I wouldn't be surprised if we see a new Fighter subclass, perhaps a rewrite (and redemption) of the Banneret/PDK, that gets Healer for free and leverages it for other benefits. If so, "One D&D" may be
very slightly more of a "4e wasn't THAT bad" revision than I had thought.
Oh my God, that...that would be
so good...I am legitimately kind of upset that that might happen, because I LOVE the concept of Iomandra and always wanted to play a game there. Which means I might have to play
5th edition "One D&D" in order to get it...