The only thing I wish from WoW since it was mentioned about multi tiers n what not, I don't think that'd be a good idea to have Story > Hardmode > Savage as mentioned it'd just be more gear bloat which is true. What I do wish FFXIV would consider is how WoW does Mythic+ dungeons as it's 1) endgame 2) challenging 3) let's you revisit content that was outdated, they could even use PotD debuffs in the dungeons to spice it up even more.

You could take Brayflox HM and turn it into a Savage dungeon+ and add modifiers to it like making enemies to 10% more dmg, healing costs more mana/reduced heals, tank threat is lower so DPS have to watch their threat instead of mindlessly spamming AoEs. It'd be easily accessible and reward gear that would be equivalent to 260 to 270 to upgrade em too via the dungeons, that way doing the challenging stuff is still really challenging and you only need 4 people to communicate with, thus eliminating getting 8 people on time for raid day.

And for the hardcore people it puts a time limit and pushes your classes to the limit incentivizing the hardcore crowd and experiment with different classes/comps while giving rewards for the efforts of everyone and if there was a leader board function there'd be that too.