I saw a post on here saying that Guild wars would be a good thing.
I strongly disagree, personally I can't stand PvP and only do what is required in quests. (I do all quest)
Way back when I first started playing (and still to this day) I enjoy teaming up with others to battle characters generated by the game.
If they do add it I hope they make it so that guilds can be designated as ones that do wars or don't do wars with other options, just like PvP and non-PvP players.
Let the person joining the guild know before joining which type it is so they can decide which type they care to join .
PvP
which type it is so they can decide which type they care to join 
.