IMHO, ELJ hit on a key driver to all of this- stock value. Stock market share prices drive the actions of companies. Companies don't get rewarded in terms of share price solely by making a lot of profit, they have to demonstrate a plan for continued future growth and bottom line profit improvement.
In the beginning, Walmart could do that by adding new stores. New markets = new income. Then, as they consumed more and more of the growth opportunity coming from additional locations, they tapped into the "grocery" segment market. Again, increased revenue and profits coming from an idea that generated growth from "new" money. Now, with an established store base, and the inability to jack up food/product pricing at a rate the stock market analysts would find acceptable and sustainable, they need to do something else, and it will probably be very different from the past model because they need to find "new" income. What that will be I don't know, but what I read above doesn't seem unrealistic to me at all. They have to identify something that will get them a new and significant revenue stream to keep the share price moving the right direction.
Additionally, there are other things they have done that could be interpreted as consistent with this "more affluent" customer strategy, in terms of who they have hired for future marketing efforts.
Personally, I dislike what they have been doing over the past few years, and I shop there less and less. Unfortunately, between doing that and making some phone calls or writing some emails, there is often not a lot more an individual can do.