FFXIV uses AI and the population has grown
Would AI work in WoW, nobody knows for sure what would happen, AI would not replace a tank, healer or dps, It would make an AI tank, healer or dps available until an actual person is found and replace the AI with them
Again, AI would not replace these classes or players, the AI would just step in temporarily, if nobody is found the AI would continue without holding up the group or queues