I don't think this is a serious assessment. For years, the core business of both companies has been facilitating the flow of used goods. Gamestop has moved strongly into collectibles recently, with a partnership with collectible grading firm PSA and the introduction of (essentially) lucrative trading card lootboxes, whereas eBay has capitalized on the same expansion of the collectibles market with new live/flash auction features.
IIRC, Gamestop recently had a "trade-in anything" day, where they accepted a variety of products for store credit. Seems an awful lot like this was some sort of test for accepting products in-store for eBay listings, or something along those lines. They already accept trading cards to send off to PSA for grading and to place into their lootbox system.
As far as efficiencies go, you can see things like shifting shipping by individual sellers to mass shipping to/from a warehouse, a much heavier footprint in collectibles, and perhaps quality control that reduces buyer disputes (this one's a bit iffy).
IIRC, Gamestop recently had a "trade-in anything" day, where they accepted a variety of products for store credit. Seems an awful lot like this was some sort of test for accepting products in-store for eBay listings, or something along those lines. They already accept trading cards to send off to PSA for grading and to place into their lootbox system.
As far as efficiencies go, you can see things like shifting shipping by individual sellers to mass shipping to/from a warehouse, a much heavier footprint in collectibles, and perhaps quality control that reduces buyer disputes (this one's a bit iffy).