Oz and Ends runs the numbers on the non-returnable, profit-sharing publishing model that Harper is trying out. I think I agree about the profit-sharing being a very dubious deal for authors.
But non-returnability... I think it may possible to construct shared-markdown and remainder-in-place policies that make sense for booksellers. I'm not sure I've seen any yet, but I'm not ready to throw the idea out entirely... yet.
I haven't seen the details of Harper's new venture, but my hopes aren't real high. People in the position to make big decisions at publishers don't often seem to have many friends who are authors or booksellers. Now wouldn't that be nice? To have a colleague on the other side of the fence that you could knock the numbers around with before you make decisions that may or may not piss them and all their counterparts off? Yeah, I'm crazy.