I get what you mean about the small shop - my mum and dad had one. It's where I learned that a 13 year old can too carry 56lbs of potatoes externally (whereas at 61 they are sadly all carried internally). Be that as it mayn't, here in SA Walmart (not quite Costco) is fighting to cement its majority ownership of MassMart which is opposed by gazillions of persons - Massmart was OK because being South African it wasn't all that efficient and bought its stuff from SA suppliers without worrying too much if it overpaid, underdelivered or just plain nothing showed up.
Walmart is a different thing entirely - there is suspicion that they will (a) expect delivery (ii) negotiate prices (3) start importing Chinese products (oh come on! As if....!) and (*) put the local retailers out of business.
The only problem with the last argument is that the "local retailers" of the kind that might be eliminated by a large superstore are absolutely nowhere near where Walmart/Massmart outlets are located. i.e. the small stores are all in the locations (read "areas of the formerly disdvantaged") where WM/MM will never tread. The small stores serve local foot traffic. As to the Chinese, it's only a matter of time before SA is owned by China anyway - and the USA had better wake up its ideas and start cozying up to Africa or the Yellow Peril will inevitably succeed.
Sorry - a bit off topic that. My initial idea was to ask Hen, does/will the new Costco actually impact any stores in your immediate area would you guess? Or are they too convenient to be displaced by a giant some miles away? (Not that Oz doesn't have cars mind but.... hey, after all it is a nation of formerly disadvantaged persons
Meade