No. Honestly basing an entire expansion on the afterlife is a bad idea. That dips into the cosmos of a fantasy universe, and quite frankly that doesn't need to be too deeply explored if the narrative doesn't require it. And we already had a whole dungeon which is a equivalent to FFXIV's after life "The Aitiscope". All souls go to the Aetherial Sea where they are reborn again as long as there is life on Eitherys, this was explained all the way in ARR. It's pretty straightforward and I wouldn't want to spend a whole expansion exploring the Aetherial Sea. I want it remain mysterious what goes on there because no one actually needs to know.

And quite frankly, it doesn't matter if FFXIV took inspiration from WoW, they only did so for game design due to WoW at the end of FFXIV's 1.0 disaster, it was actually in a good place compared to now. The game doesn't need to take whole story elements from WoW, since it should build upon what it currently has (leaving out the cosmic stuff though).