It would be optional. People will still be able to do hardcore pvp.
Making it optional would destroy the experience for most of the players that come to play MO2 that are looking for this kind of game. You don't even need to be hardcore PvP'er to prefer this sort of gameplay. I personally wouldn't consider me a harcore PvP player, but I like the danger and the feeling of beeing vulnerable to other players. Makes the reward of achieving something feel even better.
Also if you make it optional, people would exploit the system. They'd turn it on and off whenever they need it. Want to carry your stuff to another city? Turn PvP off for the time the journey takes. Even the hardcore PvP'ers would do that. This would remove one of the exciting gameplay elements this game has to offer. Games like Mortal Online 2 need wolves and sheep. Nobody wants to play on a server full of wolves. And I enjoy beeing a sheep at times.
I have played Ultima Online since 1997 and initially I supported the move to make PvP optional. But when they introduced Trammel (PvE only) and Felucca (PvP mirror of the world) it completely destroyed the experience on regular servers for many players until Siege Perilous came out. PvP was kind of like the salt in the soup (German saying, not sure if you can say that in English). The game became stale and less exciting. In a healthy community there will always be people who can help you out. There will be PKs and anti PKs who will deal with the bad guys
I understand when people don't want to be pk'ed. But there are so many games where players can opt out of PvP, but there are no other games that offer the same experience as MO2 does. At least there are no other next or current gen MMOs like this. And this is IMHO a chance to establish MO2 as a game for people with this kind of mindset. MO2 needs to fill that niche and I'm sure it can be successful, because there aren't any other games to play for us likeminded players.