Whew boy, time for GameStop to flop again. First off, getting cards graded will likely be much more expensive than what GameStop will even offer you for the cards you went through the trouble to get graded. Second, I can imagine just like any other card shop, the majority of those graded cards won't come off the shelf and will sit there collecting dust like Funko Pops.
If anyone's been keeping track, GameStop hasn't exactly had a good track record of keeping to a formula for too long, so as long as what I stated happens, I'll give it a year or so before they drop this idea altogether. Also, please don't actually sell your graded cards to GameStop for a fraction of the price when you can literally get almost 100% profits from selling it on Ebay.