If I'm understanding the graph correctly, this decline into a new "low point" for Endwalker is actually about the same numbers we had at the launch of Shadowbringers -- which at the time would have been considered an all-time new record for the game by quite a margin. In other words, the numbers we once expected of the hype driven by a new expansion release are now the numbers we get during the "worst" of patch content lull. To me, this seems to indicate a trend of upward momentum, as we will get more new and returning players as Dawntrail draws closer, not to mention the Xbox version.
Time will tell if we can get back up to the extreme peak set at the start of Endwalker, but I would also argue that was a rather exceptional moment in the game's history. We had covid, we had a rather major "WoW exodus" with a lot of streamers covering the game who never bothered before, we had the climactic culmination of FFXIV's entire MSQ.
Of course, this does nothing to alleviate the feelings of those playing at endgame right now and feel they have nothing left to do. But until we see how things shape out in the future, I don't think we can say FFXIV is literally dying as a game simply because we don't have a Bozja-like FATE-grinding zone this expansion. Not everybody even likes that sort of thing.