I'd believe it and yet I still believe this is argument fuel all at the same time. I've been digital for the better part of a few years (probably started when I got my desktop upgraded). I'd just attend midnight launch events and I'd never have to go inside during the day.
I'd say with more and more people gaming and how well it can be delivered (digitally) then people will go the easy route. Not saying there still aren't physical buyers ONLY and there's nothing wrong with that. My copy of Tomb Raider (RotTR) is physical that was delivered by Amazon on the day of release. I only went to the store for Until Dawn this year.
I got Halo 5 from Newegg with a coupon for $50. I got the digital version.
I'm not sure if there's less of a stigma with "omg, I'm going digital because I don't want to be seen at a game store because of stereotypes".
GameStop might not like it, but the developer and publishers don't care. I personally like buying digital because I keep my games. I use to just beat it and trade it in. I'd get games for less, but my collection was thin and I felt like I couldn't go back if I wanted to.
I got an email from GS this past week about 3 games that were worth $85. One was Xenoblade, the other was Dark Souls 2 (SotFS), and the other was Until Dawn. I'm not trading those in just for $85. They have told me I've owned Xenoblade for a few years now. I don't plan on selling it.