Her Ladyship read the first two chapters of The Sharing Knife.
During the Q&A, she said that the next thing was not a Miles book, nor a Chalion. I inferred, and she didn't quite say 'yes' outright, that The Next Thing is going to be another book in the TSK universe. If so, it has no character overlap - their story is done, but there are more interesting stories to be told in that world.
Oh, release date of the first volume is currently October, with the second volume to be 6-9 months later.