Benjamin Olson
Hero
I mean sure, that's definitely WotC's approach, and it is not unrealistic for how newer players will interact with the game and how veterans refer to it most of the time.People have always called the current edition of D&D just "D&D." Or like how World of Warcraft is only referred to by its overall name most of the time--e.g. "Do you play WoW?"--even though the current expansion is always the most relevant part of the game. Same for any other MMO.
It is the brand that matters in most discussions.
But everyone whose been through more than one edition sometimes feels the need (in fact quite often feels the need), to distinguish editions. And everyone who hasn't been through multiple editions but tries to discuss D&D outside their D&D group soon runs into the question of "what edition are you playing?", particularly if they ask someone for rules help. I doubt "OneD&D" a marketing (and internal corporate strategy) term, geared towards the transition period into the semi-new edition is going to be the term of choice in those situations where edition is specified long after that transition is complete.
It's unfortunate that D&D has so much baggage of using "edition" to mean "totally different sequel game only broadly connected to predecessors in mechanics" rather than what edition means with say, an academic book, where you expect it to mostly be the same content with some revisions and updates (ie: the thing they are making here). Otherwise we could just call this 6th edition (or more accurately 2nd edition of D&D Next or whatever the distinct game that is 5e D&D would be called in this alternative timeline).