Jean Grey, in a desperate gambit to save her friends from the Shadow King, uses the Phoenix force to deliberately cut off ALL telepaths from the Astral Plane and from their Telepathy.
This has some immediate devastating effects. 1) Psylocke, White Queen, the Stepford Cuckoos are all powerless without their telepathy 2) Jean no longer as the Phoenix Force, which is now stuck shielding all mutants from the Astral Realm and their telepathy and 3) Professor X's spirit is trapped in an eternal battle with the Shadow King with no relief. In fact, it is Professor X's last thought to Jean is pleading with her "Do NOT LEAVE ME ALONE", and this is heard by all the X-Men.
So we're left with everyone is suspicious of Jean Grey. Telepaths (like Psylocke) want to kill her for taking away their telepathy. Anti-Mutant groups are praising her for "stopping the mutant menace." The X-Men themselves love and miss her, but she cannot come home to the X-Mansion because too many mutants (even on their own team) hate her for what she did. Storm outright hates her for condemning Professor X to death and maiming mutants. Rachel hates her for destroying the Phoenix force and being so negligent with it.
The ONLY person to come to her defense is Emma Frost. She knows what it is like to live as a pariah. She knows what it is like to lose your body and your telepathy. She also hates Jean Grey, but she also wants her powers back. So they go on a journey.
Jean Grey, Emma Frost, and Tessa/Sage(who is being paid by Emma Frost) to find a way to get telepathy back to Mutants. Their main adversary is Cassandra Nova, who is either a manifestation of Emma Frost's telepathy or the actual Cassandra Nova, who can body swap with other people.
I'd buy that....dark and different and pretty damn earth shattering.