It's not just nostalgic reminiscence; it's people both younger and older than the game itself actually playing it and liking the experience for what it is, not a deteriorating memory of it.

I am sure that players will fondly remember Fortnite 30 years from now, but I doubt there will be as much of an active community around actually playing or modding it as there is now for Doom. If nothing else, because games like it (with centralized multiplayer only and with much of their appeal coming from active support by the developers) live and die with their commercial success.