PUBG won't "die" perse. It'll still have a large userbase for a long time to come. It's still an enjoyable game at it's core and offers much more than just being a "twitch hype game". But you can expect it's userbase to fall, it's inevitable due to the sheer size of it. It's the difference between the "death" of a game, and it no longer being the current thing (but still being pretty large userbase-wise).