This is by far the least surprising of all the line-up announcements this week. Kahn was obviously never going to return to Kamelot. There's no way "burn out" lasts this long when you've already skipped one tour to rest.
And the band's willingness to keep booking dates with guest singers shows they're not prepared to wait for him to sort his shit out.
If he takes this opportunity to reform Conception, then this is actually good news.