It's happening here too (Georgia).
What I have noticed is that when the price on a National Brand product becomes equal to or less than the Generic / Store Brand, then Walmart removes the National Brand from the shelf. I have seen this mostly in the grocery section. For example: We used to have a wide selection of about 8 different brands of canned peas, so the prices were a good spread - low-to-high. Now, we have 3 brands + 1 Store Brand - no real selection remaining.
I have also noticed that Walmart misleads consumers with it's "Rollback" pricing notices.
For example: The loaf of French Bread has a sign stating the price Was $1.50, and is Now $1.24. However, in the past 1+ year, the same bread was only $1.00 - it has not been $1.50 (in at least 1 year). I have seen this on so many products!
Now, I keep a spiral notebook with my grocery list each week. I write down the current price, and when I think it has changed, I simply review the previous weeks' list to see what it was - and I catch too many times where the prices have actually increased, sometimes a lot. (While at Kroger and Publix, the prices have remained the same, so it's not a manufacturing increase.)