Agree dungeon-crawling would definitely not exist. In this world it would probably never, ever exist.I think this might relate to what I see a a major difference between our timeline and this hypothetical one: would dungeon crawling as a game structure exist without DnD? Every alternate path to DnD I've seen in this thread doesn't suggest dungeons as a major component of the game.
CYOA would focus on story. LARP would focus on talking over fighting. Wargames would focus on set-piece battles. Video games would (and still do) tend toward fairly linear encounter paths. You might get the trappings of a Cavern of Wonders, but the old-school rpg feel of meticulously working through a hazard-filled space while making sure you have enough torches seems to be a very DnD-based trope.
As such it probably wouldn't be called Dungeons and Dragons. Tombs and Terrors or Castles and Chaos something maybe. Trap-filled tombs and the like would certainly exist, but they'd probably be very small in general, a few rooms. The whole idea of this gigantic, ever-expanding, multi-level dungeon seems to be pretty much straight out of the heads of Gygax and Arneson - and the technologies of the time, particularly graph paper. Note that even in RPGs not directly inspired by D&D they're extremely rare.