I don't think the RTS genre died; I think it evolved. Two of the most popular games in the world, League of Legends and DotA2, are RTS games. The Total War franchise keeps on kicking. Auto-battlers like Teamfight Tactics and Mechabellum mix real-time analysis with turn-based decision making.

It's the old school style of RTS that's dying; harvest resources to build units and beat your opponent. But that style of game was perfected with the release of Brood War, and the core mechanics haven't been improved on since.