The Jean Grey title is ending with Janaury's #11, as confirmed in the backmatter to this week's #10. Back in October, series writer Dennis Hopeless told Newsarama about a big moment coming for the series.
"Jean’s worst nightmares are coming. Ghost Jean went from whispering in her ear to screaming in her face, but the message is clear. The Phoenix is cresting the hill," Brisson said. "Time is running short. Put up or burn up."
While we won't spoil the contents of this week's penultimate Jean Grey #10, this cancellation comes as the adult Jean Grey returns in Phoenix Resurrection with a plan to lead a new X-Men team in February's X-Men: Red.