According to recent census numbers (which are admittedly not 100% accurate, as they're done using unofficial means and SE doesn't release actual subscriber numbers), the game has more concurrent subscribers than it ever has before, even in the leadup to an expansion. The negativity you see here on the forums and on some social media come from a combination of the people who have issues with the game tending to be the ones to actually speak up (you don't complain about something if you're enjoying it most of the time) and general human negativity bias (we notice the negative more than the positive for a number of reasons) and are not necessarily representative of everyone playing the game. FFXIV is in a pretty healthy spot right now, even if it isn't perfect, and unless something radically changes it'll probably be around for a while.