Marvel Comics Legacy and December 2017 Spoilers follow.
As a result of a mistake by Diamond Comics Distributor the December 2017 comics previews were available online for every company for a period of time before it was noticed as reported on by Newsarama. As a result, prior to Marvel’s official announcement, it appears that Bleeding Cool has mined this and is reporting on something called the Phoenix Resurrection: The Return of (Adult) Jean Grey.
UPDATE #1.
CBR gets in on the action and confirms that this is a five (5) issue mini-series.
UPDATE #2.
The official solicitation and all three (3) covers have since press time been released by Marvel here.
ORIGINAL.
It is noted that this will be number one (#1) issue of Phoenix Resurrection: The Return of (Adult) Jean Grey, but the teaser art doesn’t include that, but has the X-Men Gold team on it and noting this is Part 1 not a #1.
So separate Marvel Legacy mini-series or upcoming arc by X-Men Gold? We’ll find out soon. However, Marvel will allegedly charge you $4.99 for it.
We had thought she was coming back, as was the Young Man Logan version of Wolverine due the teaser art for Marvel Legacy #1 (spoilers here).
It is likely that the Generations one-shot (spoilers here) directly leads to the Phoenix’s return.
I imagine, older Jean Grey read young Jean Grey’s mind or somesuch and somehow prevented her own death or even the whole Dark Phoenix saga, but time will tell.