Dark Knight was cited as being a tank that uses dark magic. Nothing says anything about them being a Parry/Evade tank.

That being said, it honestly depends where 4.0 takes us. If it takes us to Thavnair, we might end up getting Mystic Knights. If it takes us to Doma, we might end up getting Samurai. If we don't get access to Sharlayan before 4.0 and we get it at 4.0, we might get access to Rune Fencer from FFXI.

It really honestly depends on where the game goes next. I mean hell, I seriously thought we were going to be getting Templar in FFXIV as our tank job for 3.0 because we were headed into Ishgard, which is a theocracy whose soldiers use spears. I never would have guessed that they would discard the "prerequisite class" system.