Both X-Men sides - blue and gold - are revealed here in this X-Men: Regenesis article on Marvel's site (h/t Rocket Stegosaurus), complete with the very villainous-looking core Uncanny X-Men team.
It appears Psylocke is playing on both sides of the fence. She's depicted on the covers (click images to expand) of both X-Men (one of the "blue" books apparently set on Utopia under Cyclops's overall leadership) and X-Force (one of the "gold" books set who knows where - maybe back in Westchester? - under Wolverine's). There must be a story to that.
Or is that not Psylocke on the cover of Uncanny X-Force? Surely it can't be a cross-dimensional counterpart, or even Revanche? Hmmm, I assume it's just Betsy sneaking off to do some black ops work for the other side.
As promised, we get family members, lovers, and ex-lovers finding themselves on opposing sides.
Cyclops is leading the blue side, but the gold side includes his brother Havok (shown in X-Factor), his sort-of daughter Rachel Grey (in X-Men Legacy), and his ex-lover (since, hey, some of those events "really" happened), Frenzy (also in X-Men Legacy); Colossus (currently looking like and wielding the power of Juggernaut) is on the core Uncanny team along with his sister, Magik, but his girlfriend, Kitty Pryde, is on the gold side hanging out with Wolverine; Magneto is on the blue side, and looks to be one of its core players, but his daugher, Polaris, is on the gold side, along with his lover, or perhaps ex-lover by the time we get to this point, Rogue; Domino is on the blue side, separated from her ex-lover, Wolverine.
These eight covers reveal only a relatively small proportion of the characters involved in the larger X-Men story, though most of the important ones are there. We see Storm on the blue side, but some of her best friends are on the gold side. Among the missing are Namor, the Stepford Cuckoos (who are teenage clones of Emma Frost - surely they'll be on the blue team?), Dazzler, and most or all of the New X-Men. Most importantly, Professor X himself appears nowhere, so what will be his role within the new scenario of a split within the X-Men?
Among the unexpected inclusions we find Sebastian Shaw posing bare-chested on the cover of Generation Hope (so is sinister young Hope going to adopt Shaw, of all people, as her new mentor?), while Toad appears on Wolverine's team.
The blue side looks villain-heavy, with Magneto, Emma, and Danger in the core team, but many members of the gold side started out as villains, come to the think of it, including such major X-Men characters as Wolverine and Rogue. As has been the case for many years now, X-Men continues to blur the line between heroic and villainous characters, with plenty of fanatics, narcissists, nutcases, and near-psychopaths running around managing to do good things to protect their world ... even though they are not especially nice people.
Exploring that blurred line continues to be a theme of the franchise, and surely that can only become more obvious, if one of the main plot points is (apparently) that the very powerful group who make up the core Uncanny group now wish to be both loved and feared by Earth's human population. That has already been revealed as Magneto's new political philosophy for mutants, and although he is not leading the team - Cyclops is - the others in the core group have apparently embraced some version of it. Potentially, it's an explosive approach for a supposed superhero team to take: it immediately makes them a team of anti-heroes, and it opens up the possibility for endless conflicts with more traditionally-inclined heroes.
There's scope for many personal and political tensions - what with opposed philosophies as well as all the complicated familial and erotic relationships that cross over the lines between the blue and gold line-ups. They don't have to be at each other's throats - this is a split over philosophies and strategies, not a violent struggle - but they'll inevitably find themselves disagreeing sharply, so we can expect to see plenty of family melodrama whenever, say, Cyclops and Magneto cross paths with Rachel and Rogue, or with Havok and Polaris. Christmas dinners are going to be a little edgy.
It's going to be fascinating seeing just how this split within the X-Men comes about, and then seeing how Marvel's writers fare in exploiting the possibilities. The Schism /Regenesis scenario has endless potential, so I hope it's realised in practice.