I don't see how this is exactly PVP related... can't they just be icons for all the new systems coming out? Devil's Hand? Loot Runs? Neph Trials?
I'm with you here.
There (probably) will be new achievements for reaching level 70 with each class, beating the game with each class. There will be a bevy of crusader-specific achievements. There probably will be achievements related to the new systems.
I don't see what about these icons is specifically for PvP achievements without some kind of official confirmation, honestly.
Just a quick breakdown of achievements by class for what I was able to surmise.
Pentagon = "Cross emblem" - Each class seems to have a "cross" emblem, but I'm not sure that's accurate. (Barb and DH one is weird, crusader one isn't with crusader icons, could be wrong)
Circle = not sure, one for each class
Rectangle = Crusader has 5, while the other classes only have four. This could be because crusader is new. Crusader is kind of demonic too, so that could be wrong as well? But seems to fit the theme.
There are obvious skill achievements in between each classes rectangles. Diamond skin for wizard, sentry for DH, Ancient Spear and Weapon Throw for barb, etc