The "Assault Weapons Ban of 1994" has been thoroughly studied, and proven that it made no discernible difference on crime.
I hate to be the critical editor of arguments. The statement is true but if you use it, you'd better know all of the story. This was reported in the scholarly literature. In fact, I heard it first presented at the meeting of the American Society of Criminology. Here's a reference to the work:
https://www.ncjrs.gov/pdffiles1/nij/grants/204431.pdf
In their presentation, they hypothesized that the reasons for the lack of impact on crime, were:
1. Existing stocks of weapons and magazines (in the millions) were enough to satisfy most demands through resales.
2. Weapons of equal efficacy continued to be produced in large numbers. The Ruger Mini-14s come to mind. However, AR patterns without the cosmetic features that were banned, were produced in large numbers. I read that about 730,000 without the silly thing that goes up were quickly produced. Such still goes on, you cannot buy a Ruger PC 9mm carbine in some ban states if it has a threaded barrel but you can buy one with an unthreaded barrel.
The authors concluded that stricter bans - like all mag fed semis and confiscatory laws, no grandfathering - were needed to impact crime. That's the second part beyond the statement that gun folks like to quote. If you argued with a smart anti, that's the reply.
Now some of the smarter antis have picked up the problem with the initial AWB. Some have not and just parrot the original. However, other don't and will go for a total semi, turn them ban. They know that many won't be but the ban will make the guns useless for law abiding citizens legal usages. It will strengthen a cultural change that guns are bad. As we age out, the hidden guns will be turned by many heirs.
As far as other major chains picking up from WalMart, I doubt it. They have to invest funds, modify stores, train personnel for an increasingly socially unacceptable product with a limited financial incentive. I don't think many corporate boards will do that.
Probably the WalMart board gets as many positives on this action as your negatives. Not to say that you shouldn't but be realistic. The greater culture war is being lost for various reasons.