It would open many doors over the course of a few decades of market correction. Just cause walmart closes shop doesn't mean local poor people suddenly have the capital to start a business and compete. It's why ghost towns are still a thing. When the oil derrick town dries up, the driller who now lost his job isn't gonna just start drilling for oil now.
Why nationalize them? What would be the point? The purpose for nationalization is to give preferential treatment to the state. Walmart already does that and (in my personal opinion) does for the people as well.
Although the only thing I wish they cut back on was their employee culture cult stuff. It reminds me of McDonalds where you have to say thank you to a supervisor after everything, even if they're yelling at you to be a dick. It's like the f'ing military. That kinda brainwashing garbage needs to go.
Also, the overwhelming majority of people are driving to Walmart so even if significantly less convenient they can also drive somewhere else.