every MMO have affected wow over time...every new feature people love on new MMOs blizzard eventually add it on wow. Barber shops, aoe loot, even class design...transmogrification..also in mop we also had the "no tag" for named quest mobs thanks to gw2 no tagging system and how people loved it. If ESO will be successful wow will borrow some things from it too...
Also ESO have a great lore and lot of previous single player games with a huge funbase, like wow had with warcraft RTS. Maybe ESO will force Blizzard to go back and respect again the wow lore and we see again a good expansion (just don't tell me pandaland was in wow lore, I know if you ask 200000000 people about wow and what they know and like about its lore, no one would tell you about pandaren)