I don't think Gamestop going away will have any impact on physical media for console games.
Your experience buying games at Walmart sounds strange to me. When I go to a large store like that (we don't have any Walmart here) to buy a game, the process is simple. I go to the shelf that has the games. I take the game I want. Then walk over to the register and pay for it.
Which leads me to my final point.
Last time I bought something game related at a store was my PS4 in Feb 2016. I had already paid for it online. All I had to do was show up, show my ID card, and then take it home. The workers were polite, wishing me a good day, or to enjoy the product, but that was it. And I preferred it that way.
For those such as yourself who prefer to chat with the staff about games, I can understand that, and that would be a loss for you. But shouldn't be a hindrance for you to buy games physically at a store. You having a bad experience at Walmart would though. But I don't know how prevalent that is across your country. Are there no stores that let you just pick the game you want off the shelves and then head to the register? Or reserve/pay for it online, and pick it up at the register when you get there?
I mainly buy games physically online, because they tend to have better deals. In particular Amazon. Even on Day 1, it's usually at least slightly cheaper than what I'd find in a physical store, and the shipping is free, so that's what I usually do. (A few years ago I shopped on another site that was ridiculously cheap. Brand new games would be no more than $30, and some times lower when it had a campaign going. Free shipping as well. Though unlike Amazon, delivery took a few weeks. But it was well worth the wait for that price. I bought a lot of games from there, but sadly they stopped selling games after a while. But still sell other products.)
Anyway, even if dedicated video game stores go down, large electronics chains should still carry them. I don't think Bic Camera or Yodabashi would stop selling games in Japan any time soon.
Games at Walmart are under lock and key, so you have to go and drag down an associate to get them, and Walmart customer service is complete ass. For the most part, that isn't the fault of the floor associates as Walmart stores are almost always understaffed. There is no "in and out" with Walmart. Plus, the big-box stores tend to carry a limited selection of video games compared to Gamestop.