If they will raise age rating of the game along the way in entire world and not just in a couple of countries (I look at you, Russia with 18+ age rating on FF14) - sure, why not. It's about time to raise the rating anyway, honestly speaking, given all the things the game has.

Sounds like a nice RP addition, especially considering that it's not like WoL doesn't drink - Dwarfs beast tribe quests and last Role Quest you get after finishing all 4 of them quite openly shows that we do, at least occasionally. I probably wouldn't want to see any long lasting sub-effects, but a couple minutes debuff could be fun (not in battle, though, since people fail mechanics even without being drunk).