Trickster Spirit
Explorer
???
I think the main issue is a lot of the "problems" are actually playstyle preferences. So far usually each edition has focused primarily on a certain playstyle preference.
Hands down the thing I love most about Next is it's baked-in ability to support different playstyles. Whether it will be flexible enough or not at release to support OSR, 3.5 / Pathfinder and 4E players all at the same table is one thing - some things have to be decided in favor of one playstyle or another at the table level - but it's already demonstrated that it's capable of emulating any one of them.
Of course, a lot of players won't see the point in a 5E that emulates their edition or clone when they already have their edition or clone. I mean, from the start 5E been a compromise edition. For a while the argument that it would attempt to please everybody and thus please nobody sounded justified, but at this point I can actually see gamers with different preferences sitting down to play it together. Maybe friends with drastically different favorite games have been wanting to play together again, they just can't stand [insert vile, hated edition here], and Next offers them a middle ground. Maybe, just maybe, it'll be easier to get a game started with strangers if it's Next, because edition partisanship has always made that a hassle and now it's less of an issue if you know you can emulate your favorite edition's crunch-tastic tactical character next to another player dirt simple fighter, or vice-versa. Maybe a group will find the system they've been playing satisfies their playstyle, but its rules are too tightly woven to simplify or house rule easily - Next will offer them a lighter fare that can be tweaked to emulate their favorite bits of their old game.
Combine that with a Basic game that's perfect for introducing new gamers to the hobby, and that scales up easily to something crunchy enough for the more die-hard fans, and I'm willing to bet Next will do well and at least attempt it's stated goal of uniting players of disparate editions.