I refer to MechQuest when I think of Academy content. Basically, each "class" levels up "skills" for the character. The skills would work like in RuneScape: passively, which affect stats, occupations, and environment manipulation.
This occurs while doing non-combat quests getting you affiliated with the academy. From the academy, you can accept events and missions (like in GetAmped2) which send you to instances throughout the world (like in Vindictus). While, in addition, you can also open-world, allowing for more content.
I only used the level 1-20 to explain how much content it has, but honestly the levels only exist in concerns to the skills - not the character. Characters could have Ranks, but honestly that won't say much about them - which means PvP will be more involved, as the character would be classless and rely on the skills they've trained rather than basic level comparison.
So, it would be a mixture between sandbox and dungeon, with dungeon being released first and foremost to get players in without having to use too many resources.
That being said, it would mainly be explorative in nature than an all-out brawlfest. Even so, the combat is meant to be fully-interactive, even cinematic. So, it gives more of a proper RPG feel than most Online games today.
The above is based on the design of the world we've been shown in the show. Normally class and leveling systems would NOT work in that world, period. And it's not impossible to create the above: All of the content I explained has already been done. The team just needs to combine it.
Ooooh! We live in the Highlands with our kilts in the wind! We're the Tartan Army, come join us, my friend! We look so dandy, jolly, and bloody right! We wear tartan because of our Tartan Pride!