I am going to hardcore disagree with you there. At least on the abysea part.
The game was in steady decline before abysea. It dropped from its peak of ~600k active players to around 390-420k over a 8yr period.
After abysea launched within a year it dropped by an additional 60% of that number... and this was at 1.0 not a game that actually was stellar. There was a reason why when XIV 1.0 failed hardcore and people never did go back to XI.
The Game shift away from guild focused content, negating ~25,000 hrs of content that existed in the game before it, Destorying the whole leveling process, ruined crafting, ruined jobs entirely, Literally made you a god ingame by using a stupid abysea potion thing. Abysea is when what FFXI was officially died. FFXI now and what it was Pre abysea is as night and day as 1.25 and ARR. I love how people say other wise. Look at the sub count, look at the reason why people quit. It is not that hard to see.
FFXI was not a nitche game it was mainstream mmo at its launch, and it was one of the most success mmo launched in that era one of the few to ever pass EQ. WoW redefined the genre, shifted it from midcore to hardcore only to allow the casual gaming audience to play. There is no way for a hardcore only game to ever compete with a casual game. Example which game is better Pokemon or Darksouls for example. I would say Darksouls but I bet nearly 10,000x as many ppl play pokemon.
The masses of FFXI did not leave and go to WoW when it was gaining millions apon millions of subs because they wanted that hardcore game, not an easy mode mmo. When SE tried to shift it to a casual game. Well WoW and all those other games were simply a better casual mmo then it so they all left and never came back.
I had a guild of 74 ppl pre abysea doing ~60hrs of guild events a week. Once abysea launched all but 7 ended quitting the game due to how bs the changes were and how little there was to do.