A few weeks back, TerraDave posted a poll where he asked people
"What must D&D have?", and I found the responses interesting, and they gave me a pretty good definition of D&D.
With classes, Fighter, Cleric, Wizard and Rogue all had 75%+, and then a big drop to Paladin as the next most popular at 38%(Ranger was omitted by mistake).
With races, Human, Elf, Dwarf at over 80%, Halflings at 64%, then another big drop to Half-Elves at 35%. In fact, all of the monster choices listed were considered a more important element of the game than the Half-elves and the less popular PC races, with the exception of dinosaurs at 29%.
Polearms rated as a more important element of D&D than Half-Elves or Paladins.
Now this poll had only 301 respondents and obviously couldn't list all possible options, so too much shouldn't be read into it. Planar questions are obviously missing. If I choose 60% as a threshold for inclusion in "ENWorld Poll D&D", I see that D&D is a game:
Where there are six abilities, all the platonic solids are used as dice, but the d20 is most important.
Where the PCs are chosen from the races of Humans, Dwarves, Elves and Halflings and take on the classes of Fighter, Cleric, Wizard and Rogue.
Characters have hit points, AC and saving throws. The classes have levels, some have spells. They win gems, gold, magic items and experience points.
Dungeon, city and wilderness adventures are all important. Characters battle a whole list of iconic monsters, with only drow, giant/dire animals, dinosaurs and the tarrasque failing to reach 60%.
If Wizards produces a game that satisfies these criteria and calls it D&D, then they'll satisfy at least 60% of the respondents. I'm one of them - I'd look at that game and call it D&D as well.
And from the previews I've seen this seems to be exactly what they're doing, with one exception: saving throws. And I'm guessing they think that replacing saving throws with defenses will be for 4e what cyclic initiative was for 3e. Hated until people use it.
Wizards must have better survey data than this little poll, so they they must have a better idea of what the D&D consumers tend to consider essential elements of D&D. They look like they're going to provide those elements but they're willing to alter everything else.