osu! is dead in the sense that most communities have more or less diminished overtime.
years ago, like before 2015, osu! would have a lot of active sub-communities compromised of national groups, mapper groups, certain mod-combination player communities (FL), even forum shit posters had their own communities etc. I see less of this compared to back in the day.
osu! over time has strangely become more of a homogenized game in my opinion.
what I mean by this is pp-maps have stomped out most players with unique skills and playstyles from the leaderboard. not saying that all people in the top-100 are, obviously there are many players with incredible skillsets but a majority of them have similar skillsets so there is less incentive to look up to as many different top players as compared to back in the day. On top of that, overall this game community is a lot more westernized/western dominant. Before there were clear western and eastern (asiatic) communities.
I know that numbers wise, osu! is more popular than ever before in it's entire history but osu! and it's community has lost a lot of it's original culture to the point where old players returning after 5 years would find this place unrecognizable.