Perhaps there will be some complaints (in fact there are a few already), but certainly not a lot. In the US and Mexico, whether or not a merchant accepts contactless is very rarely or never a factor for people to decide whether or not to shop there. People make that decision based on anything but the acceptance of contactless payments. Heck, if pressed further to either accept contactless or drop card acceptance altogether Walmart could choose to go cash only in both countries and it would make very little difference, if any at all.
I disagree... though I have no supporting documentation, I would venture to say that Walmart is the store of choice for the "paycheck to paycheck" crowd who stretch their finances by relying on credit cards...