What is interesting to me is that this will inevitably lead to people arguing what a new edition actually is. I mean, how much has to change before you call it a new edition? There will certainly be people that will state, "Well, they kept the abilities and classes and subclasses the same, so it is not a new edition," while others will say, "They changed how background feats and bonuses work, and took species and changed the heck out of them, so it is a new edition."
Which is (part of) why I consider "One D&D" to be clearly a half-edition. The argument from "above," as it were, one more or less presuming that a game update is a new edition unless it keeps changes sufficiently small. The other argument from "below," which is what I have used previously, presumes a change is
not an edition unless it crosses a sufficient boundary.
"One D&D" is highly comparable to the 3.5e "revision." Some classes are getting dramatically changed (Warlock) to the point that they won't be compatible with one another. Others are likely to get significant but not total reworks (Bard, Druid, and Ranger seem to be high on that list—notable since Ranger was one of the heavily modified classes in 3.5e), and there will be a major overhaul of the spell list and character features. Some spells aee being heavily changed, and many new ones are being added. New BGs genuinely replace old ones; you will need to perform some conversion (not a
lot, but some) to make use of them. Long rest design is almost totally replacing short rest design because people don't actually play the game in a way compatible with a heavily hybrid model. Etc.
Conversely, much is not changing. The damage scaling amounts, degrees, and levels are the same or almost totally equivalent. Extra Attack and cantrip scaling still happens as intended, for example. Monsters will be
structured differently, but
function essentially the same, and items will work almost completely the same. Hence, there will be little to no need to convert most modules, except those which set specific backgrounds or use pre-defined characters for players to use (which I don't think any first-party products have done?)
So, it's pretty clearly
less than a total edition break (the argument from below.) But it changes rather a lot of things that
are part of such a break (the argument from above.) As noted, these changes are quite similar to the 3rd->3.5e changes, meant to tighten up design (
meant to, anyway...), fix loopholes, and bring the experience closer to the original design intent, while enriching the early game experience.
Hence, whatever they call it, I think it is both reasonable and practical to refer to it as 5.5e. It's not an edition change, but it also
isn't literally just offering new alternatives which function ever so slightly differently. The Warlock alone proves that much; it is clearly a
replacement of the existing (and, IMO, infinitely more interesting) Warlock class.
