Be careful what you wish for.
It 1 point in time, I had a gaming group that consisted of well up to 10+ people. However, people grow up & apart, & the group pretty much fell to pieces (& continued to fall to pieces, after a few attempts to build things up again). Gaming for me has suffered severely since those days.
Ideally, I'd recommend finding a middle ground. Implement things that everyone can agree on (rules and setting-wise), and run the games that way. Also, if you switch genres (from fantasy to supers or sci-fi), why not see about switching game systems as well (or, at least use d20 with different in-game options/house rules). It's only been 6 months--time has a way to change people, attitudes, and opinions. It could be possible that the D&D-only crowd may tire of it, and want to play another game for a while.
As for established vs. homebrew, I'd say it'd be wise to see what likes/dislikes about these two. Also, do the ones who favor established settings all like the same established settings? Do they all like Greyhawk, for example, or do some like Greyhawk, some like Forgotten Realms more, one or 2 like Eberron, 1 person really likes Dark Sun or Planescape, etc? How strict to the canon do pro-established-setting players want to be? (Very close to canon in game & books? Not close at all? Use only stuff in the rulebooks but not in books/comics/computer games/etc.?) Along the same lines, to the ones who like homebrews like the same sort of homebrew, or are there differences there (low vs. high magic, cinematic vs. gritty, core rules vs. new supplements/unique creations, etc.)?
If the group stays together, I'd suggest going with a middle ground approach. Use a variant, "What If?" version of an established campaign setting; perhaps the world has become low-magic after a massive event, but with a few secret locales filled with high-magic areas (that aren't able to spread out & cover the rest of the world). Stick with D&D for this, but if the group tires of this game, switch to another genre using another system.
Hope this helps some (if any).