My erroroneous assumption, and my bad phrasing.

How's this for a restatement? "There's no reason a book should ever have to go 'out of print' today."

Of course, actually, there are. Ian may be actively trying to re-sell the book and not want to have a Wildside edition out there getting in the way of the resale. He may be planning to revise it. He may have decided that the potential earnings are not worth the hassle of dealing with a specialized publisher. And he most likely doesn't want to try to do it himself.

Plus, there are those used copies readily available for sale everywhere.

Mike