“6e” will attempt to deliver on the modularity that was promised in the D&D Next playtest and in fact, it won’t be marketed as 6e at all, but rather as a series of optional rules mods designed to be fully compatible with 5e. In practice though, most groups will end up either sticking with vanilla 5e or using whatever mods get taken up by the Critical Role cast and calling it 6e. There will of course be plenty of groups that use their own particular combination of 6e modules, which will end up leading to a three-way edition war between 5e grognards, “default 6e” players who use the mods popularized by Crit Role, and “Build-your-own 6e” players, who will nominally be united under the banner of DIY (as Gygax intended) but internally war with each other over which mods are the best to use. This will split the fan base as it had not been split since 2e.
In response to this, 7e will go in a bold new direction, doing away with rules entirely. Of course, it will maintain the sacred cows such as the standard lists of races and classes, the 9-alignment system, the six abilities each rated on a 1-20 scale with PCs generally falling in the 3-18 range before racial adjustments. But none of them will have any actual game mechanics attached to them. They are all purely descriptive, even the stats with associated numbers. There will still be dice (wouldn’t want to leave that sweet branded dice money on the table), but they’ll be rolled whenever the DM feels is appropriate, and the results will mean no more and no less than the DM decides they mean. Published adventures will describe scenarios in which to place the characters but will have no rules for resolution, encouraging the players and DM simply to narrate whatever they think will make the best story out of the scenarios described. Supplement books will consist of lore, improv advice, story ideas, artwork, and lots and lots of random tables, but nothing that could be reasonably described as “crunch.” Mike Mearls will occasionally tweet his musings on the brilliance of this no-rules-just-right approach to game design, and how the problem with previous editions was their crippling focus on things like “gameplay” and “mechanics” that only ever really served to get in the way of players’ and DMs’ creativity.