No offense, but this won't ever happen. It would anger players who dedicated themselves as a DRK tank, go against this game's philosophy of DRK being an unothodox defender against injustice to which their darkside is currently only a mean to an end, not an occult art and it would invalidate all work since 3.0 to design DRK as a tank and not just a beefy dps.

That aside, tanking in this game is currently very close to being a glorified dps - tanks are basically dps that specced into defense for survival, so it isn't so far fetched to technically play a dps-y dark knight.