>I am unsure how a Gamestop/eBay storefront would do. Physical manifestations of "eBay stores" have existed in the past and none of them did very well long term.

A key here I think is the easy gradual transition here because Gamestop already has the used games business they could slowly integrate that into listing used games on eBay that were received at stores and then add related categories step by step with collectables and consumer electronics. There'd also be options of ebay items delivered to store which increases store traffic and doesn't involve giving strangers on the internet your home address, and there might be opportunities there to enter logistics and lower delivery costs for people.