Not much considering how much inventory space they take up. The main draw of selling game consoles in your store has pretty much always been profiting more off of the games sold with it.
OT: The writing's been on the wall for a while. Unless retailers can find a way to adapt (can't think of one myself), the digital era was always going to leave them behind. I wonder when the tipping point will be. What percentage of games sales will be digital before most major retailers decide the consoles they play on aren't worth the shelf space? Maybe the big 3 will give them a bigger cut of the console sale to counteract that.
I think they should do more custom PC building... Selling PC parts especially the customization parts, led etc... Also they should dip into Home Theatre equipment.... The next step for a gamer is to have a nice TV and sound system, maybe a videoprojector or even a dedicated room... I know those are different businesses but they tie in pretty well and could be a good way to keep them afloat... I know I have being going full digital since the 360 and don't intend to look back...