http://www.newsarama.com/pages/Marvel/Austen_Leaves.htm

NRAMA: What plans did you have for them that the readers would not see in the pages of the monthlies, or sometimes, bi-weekly comics?

CA: So many. Soooo many. I even have a few scripts that Marvel owns that will probably never see print. I had a lot of plans for Warren and Paige, more emerging angels, and Warren becomes reclusive as a world of infirm and cripples make pilgrimages to him for him to attempt to heal them. The return of Azazel. Sinister's death camps. Big things for Havok and Annie and Carter. Some surprises with Polaris. Some twists with the new Xorn. A relationship for Northstar. Josh Guthrie was going to have a lot happen to him. Mindee, one of the cuckoos, had a growing role. There's a few jolts coming with Juggernaut, that would have played out differently if I'd stayed. My head was loaded with X-stuff for years. I loved all the characters, really, and had plans for them all. As I said, this was a tough decision, and I had to remove my personal feelings from it. In the end, it's business.
I'm guessing the rumours about him being allowed to do very little with NS because of editorial may well have been true then.