You could argue that for multiple genres! Is today's Call of Duty not just a remix of mechanics created decades prior?
Total War, Anno, etc. Highly successful series with new and coming releases with many mechanics evolved and built upon the classic RTS formula.
> As a genre, RTS is dead.
It has shrunken, I would consider it far from dead. There is a limiting factor when we consider the classic RTS formula, it's essentially PC only. Many genres work across consoles as well or were adopted to work there as well. eg. Aim assist in every console FPS. Mobile doesn't work either, touch + classic RTS doesn't mix. RTS has thus a limited audience it can appeal to. But dead it is not, Steam's player counts for Strategy --> Real Time Strategy speak for themselves.