Guild Wars 2

I agree, no matter how much it will cost to change profession/class many who have invested time in their main characters will do it. Arena Net has nothing but to gain from this. Put a high price in gems to change class and that will bring big income for them.

Change and be available after a character reached level 80, completed story line then decided to pass (die) after an epic quest (which will require gems, a lot of them to fuel the magic behind ritual – insert hero choice here), if they decide to do it in the first place, then as an entity in the Underworld decide to grasp for life, a cycle of birth, death and rebirth (this is where karma is used) to a new life as another race and profession (all costing a great amount of karma), losing no progress from the past life (quests and crafting), thus taking the epic journey of the hero to a new grand immortal perspective as a chosen of destiny.

This is just an idea with an enormous potential enriching the story line for each hero.