Random Query: The Trinity System

[DPZ2]

To begin the conversation...I'll list pros to changing to a system of self-sufficiency.
Pros:
- Combat becomes completely reliant on player skill & strategy.
- Everyone can be the class they desire. A true end to: "___ job should be ___ role."
- No longer will folks debate on ___ role needing to do ___. (Ex: Healers must do dmg in addition to healing. Tanks must do ___.) As Damage mitigation, damage dealing, & Healing will be more or less each player's responsibility and not 1 roles.

I think you just defined a game in the First Person Shooter genre. There are plenty of those on the market. Many have RPG bits-and-pieces to them, and of course, cooperative modes to encourage people to play together.