Mom and Pop stores will not completely disappear because of a fact already stated, sheer laziness of driving to a Tesco or Big C. They have been greatly affected though and will not stay in business unless they offer products the big supermarkets do not. My wife hops on the motorbike at least three times a day to go down to the corner shop, so if you multiply that by all the villagers it adds up to quite a sum.
Items we buy from the corner shop are chips and goodies that I do not eat, cooking ingredients that the wife does not buy at Tesco or Big C, cold beer when a friend pops by and the occasional liter of gas for the unlicensed motorbike that is used for the frequent trips inside the village. What I do notice is that prices vary and the shops on main roads charge much more than those along the small sois in the village.
I still would not invest in a Mom and Pop shop however.