I don't think single-player games will ever fully go away (I really hope not anyway) but online-centric games are undoubtedly the du jour. That said, this may not be the perfect analog, but when iPads and Kindles came out, everyone bought their books digitally and now people are moving back to physical books. In other words, trends ebb and flow. Sure, Fortnite and PUBG are big atm but that doesn't mean online games will be the big thing forever. Hope that makes sense!