Charles Soule, writer on the Astonishing X-Men maxi-series, has just told a room of retailers at New York Comic Con that the whole point of the book is to bring Charles Xavier back as a living character in the Marvel universe. So that's what's happening.
So don't expect him to just stay as an astral figure as we have seen in recent issues.
The reason he comes back is different than anything we have seen before. It is meant to happens first in Astonishing X-Men #6 and 7. As with Ron Garney returning to Daredevil, it is possible he wasn't meant to have said that, either.
This is all coming out of Marvel's adjunct to Diamond's Retailer Breakfast ahead of New York Comic Con, happening today. You can catch up with any other Retailer Breakfast announcements here.