Every time we worry that singleplayer games are dying, it turns out that what seemed like death throes were actually just hiccups, or the onset of a sneeze. Singleplayer games are thriving: 43 percent of Steam's 2020 best sellers are games that I consider primarily singleplayer, and that's being picky.
Are single-player games better?
Single player games allow for much richer character growth and interactions. The sum total of narrative, emotion, characters, and artistic elements give single player games an advantage multiplayer games may never achieve: something I can only refer to as literary significance.
Are RPG games dying?
RPGs aren't dying out, but developers need to focus on what makes an RPG great if they want it to survive.