I thought that Walmart only did online pre-orders. So we're not likely to see any of them on the store floor. If pre-ordered for in-store pickup, it'll go straight to the service desk, otherwise, it'll just ship.
My Walmart got a dozen. I was in line with a few moms and some gamer types at midnight last night. We bought 10 and I'm sure the other 2 were gone before the sun came up.