In general the stock sites don't approve things that people would want on their walls. How many times have we, as a group, complained about images being rejected for "not stock" or "over photoshoped / to artsy / to designed"? The stock sites want themes that apply to concepts or isolations that can be manipulated by designers to create what they want.

The other big part of this will come down to marketing. To my knowledge IS never marketed the concept of coming to them for prints. Designers, in general, are creating an advertisement - not looking for a finished art piece to hang on a wall. If they can market this to people who purchase wall art on a regular basis - like interior designers - then it may work out ok.

I'd agree. One of the first adages I heard about this game was "If your image looks good enough to hang on a wall ... then it probably won't be a good stock image"

I sell my landscapes at the market from $100 to $200 mounted. There is about $60 to $120 margin in that.

The stuff I sell for stock does not get the same attention to detail, does not take ages to get the right shot, and does not cost travel money.

I had originally thought about going that route a few years ago as I do mostly landscapes and nature oriented stuff and then do the market tour thing.  I know a few guys locally who do that, but geez you gotta put out alot of money up front mounting a number of prints and then having some kind of presentation booth, plus spending all weekend at these things only to sell a couple of prints if you're lucky.  It's a lot of work and alot of money up front and then continues being alot of work. 
Through Zenfolio my mark-up for prints is around 15.00 depending upon requested print size and Zenfolio takes care of everything.  I'd much rather get a smaller amount and not go through all the up front costs and related work than try to do it all myself and have alot of money tied up in prints that may or may not sell. 
Since it looks as though we won't be getting paltry subscription royalties for prints, I'm for the move.  I'd just like to know who they'll be using as a print service.

I don't think printing is going to be limited to "art".

I think this is such a fantastic idea and I plan on using lots of my credits on making canvases of my images as I planned on doing this at some point anyway