[hrdwdmrbl]

Not that I have any interest in launching an exchange, but I do see what you mean by the possibility of an exchange becoming quite abstract. If housing deeds are traded then a housing marketplace is an exchange. If cars ownership is traded then a car marketplace is an exchange. If in-game items are traded, it's an exchange.

Could one think of stores as one-sided exchanges, where resale is just not natively possible? Does Google operate an ad exchange? Is iTunes an exchange? If digital goods ownership were on a blockchain then resale would be possible... What about physical goods?