So PC gamers rarely go to the store to buy a disk anymore. According to DFC Intelligence, via PCR-Online, 92% of sales for the PC gaming platform were online. This number seems to be based on revenue, rather than units sold. It includes both full games purchased from Steam, GoG, and other distribution services. It, also, probably includes free-to-play revenue, DLC, and so forth.
Of course, this also suggests that retail sales of PC games has quite a bit of money floating around still. While sources lump several categories together, we could still be talking about a hundreds-of-millions or low-billions order of magnitude (USD). Of course, these are personal, mental math estimates. A grain of salt is required and, in this case, probably good for your (mental) health.
Watch your cholesterol, though.
Again, this is one of the advantages of open architectures. Companies and organizations are allowed, because no-one can tell them otherwise, to try new things. Sometimes, they end up being gold mines that lead to industry revolution, whether we consider the specific positive or negative. However long it takes, it wins. It eventually finds a way, and then the blob tumbles along.