OH yes silly me. I forgot that Steam machines are currently outselling PS4s 5-1 every month.
I said "dedicated gaming hardware". And yes, someday discs will be gone, but that's not going to happen anytime soon, especially since not everyone can even have at least a measly 5Mbps+ download speed, me included.
I think you're looking at it the wrong way. Physical is the way it's always been done, so it's just still around. But if suddenly it wasn't an option any more, or was an incredibly limited option, it wouldn't really be that big a fuss, in the same way the transition was with PC gaming, and really PC software in general.
If they do go the digital only route, you'll probably still be able to go into a store and buy a card with a product code on it to redeem in whatever online store exists, just to help out those people that find online shopping utterly confusing for some reason.