If it was a store struggling to make ends meet, I'd leave the merchandise be. Since this is Wal-Mart however, a mega corporation with a known track record of treating their employees like **** right down to the awful pay, I personally would sneak a copy of the game home a day or two before its to be sold to the public and upload gameplay footage to Youtube. As I tend to keep to myself, no one at the store would know it was ME who did it
tl;dr: Not that I advocate it, but in terms of shoplifting, multi chain corporation esque stores like Wal-Mart don't really care if some of their merchandise goes missing compared to a Mom and Pop store where you're more likely to get shot/beaten with a metal bat if you try to steal their stuff. Still gotta be wary of cameras though and anti theft doo-dads.
On Topic: I fully expect the internet to bleed red on Friday with the gargantuan amount of SSB4 info we shall be getting.