Will the incoming thief job be a DPS or tank?

[Aegis]

Uhm, how much sense does it make for a thief to tank? a thief isn't supposed to get *caught*
a thief wont use heavy armor, or def skills, so they will get 1-shot=bad tank, unless they get 100% dodge chance, which wont happen (maybe 1-3 hits, like mana wall, or such, but that wouldn't be enough, for same reason BLM don't make good tanks)
and how much sense does it make for THF, to aggro? more likely they would get aggro-reduction skills.

I don't know if you ever played XI, but the Ninja job there was a highly evasive DD that became a tank through popular usage. It managed this by use of two spells: Utsusemi: Ichi and Ni that created 'shadows'. Each shadow took a hit that would have hit the Ninja and disappeared. Ichi created 2 shadows and ni created 3. Ni shadows could overwrite Ichi, but not visa versa. The trick to tanking as Ninja was managing your shadows so you rarely got hit (especially because getting hit with your shadows down could interrupt your casting of the next set, while maintaining enmity abilities.

Eventually, SE gave in and gave Nin some enmity+ gear, but it was an effective tank anyway for single mobs that hit slowly, but hard.

As for the Thief class itself, it's role in XI was enmity-management. It could take hate from other party members (with merits). Also, it could plant hate on others (and doing so increased the Thief's damage)