The point is not how op you are, the point is that the quest is level 60, these are therefore level 60 elite. As I am only one of two people I know of to ever defeat a level 75 as a level 60 charater, I am confident it is impossible to defeat one of these level 75 world bosses as a level 60 character.
I did the arkana quest series back in chapter 3 for the level 50 elites. Those were extremely tough, but doable by a level 50 character. These new elites are impossible to be done by a level 60 character.
edit:
I see a couple of post in here indicating that players can defeat the level 75 world bosses, which is quite true. The fact is that all those post are made by players that are level 72 and up. I challenge any of them to attempt the bosses with level 60 characters, or even their level 60 side. Even if these are actually level 70 elites, which conflicts with the quest being level 60, trying to take on a level 75 boss with a group of level 70 characters? I am not even sure that is within ppk, valkrye, ragnork, or any other guilds ablities. Where is there any other instance in the entire game that the bosses are 15(or even 5) levels higher that the quest?
The thing is that it isnt about how op you are or arnt. This content was released as being so convolutedly and obviously broken, that is the point. We, and gameforge/runewaker, dont need new content, we, and gameforge/runewaker, need the content currently there fixed. Not just the chapter 5 stuff, but the chapter 4, chapter 3, chapter 2, and even chapter 1 stuff that needs to be fixed.