I believe comics would fall under DSD (Direct Store Delivery). Some of the bigger book store chains have them, and that's how they do it. Categories across the store use this to manage, stock, and straighten up shelf presence without dedicating their own people. I know Snack Chips, Soda, Bread all use a DSD service. With DSD, you don't need to do anything other than code the UPCs into the system - an outside vendor takes care of deliverying and stocking the merchandise for you. I think I've even seen these people managing the greeting cards section, which wouldn't be all that different from managing comics. You may have some issues with coding in limited series issues, but maybe that means you don't carry them. Lord knows I would rather they just plug those stories into the main titles versus restarting the count on new titles all the time. (I'm looking at you Transformers).
As for unsaleables, I thought magazine and comic companies used to absorb those costs if the comics were unsold? Maybe Marvel and DC moved away from that, but I think that's how they still handle magazines that are out of date. That limits the risk to retailers, even if they end up absorbing some of the cost.
I don't subscribe to the space issue though. TRU has a silly layout for their comics that ends up getting them all torn and disorganized at my local stores. Just get a wire rack that spins like you'd find at B&N...I'm sure Borders has lots of them for sale cheap.
That doesn't take any added space from the aisle and you can move it wherever you like in the store. I just think it's a lost opportunity for retailers and the industry. I'd much rather buy my kids a comic than these crap Mighty Beans or Fighter Pods. If you can sell a lego minifigure for $4, you can sell a full length comic book.