Hong Kong living space is a lot tighter with families typically crammed in a sub-500 square foot home. That's for 3 people + a helper from the Philippines or Indonesia. Nobody in their right mind will stock up quantities that Costco offers. For young professionals fresh out of university, they can barely afford those mini-apartments under 200 square feet which can't even fit a proper fridge and have to build a bed above the TV in the living room to save space. They won't be buying in bulk like their other middle class counterparts in Canada or even Taiwan.

Getting space to build a large warehouse will also be a challenge. No Hong Kong retailer, not even the established duopoly, has anything close to a store of that size even in the distant suburbs. So they're squeezed on both the supply and demand sides. I think the recent craze of Hong Kongers popping to Shenzhen's new Costco is just a temporary fad because it's new. It'll die down after a while. The reason why Costco or Walmart can't make it into Hong Kong is purely a real estate one. Is there even a superstore in midtown Manhattan? Perhaps that's a more appropriate analogy.