Summoner used to be the pet job. In it's first incarnation, you had three pets to choose from: a magic DPS (Garuda), a melee DPS (Ifrit), and a tank (Titan). They had hit points and a combat AI. You had pet-only heals, the ability to give direct commands (attack this, wait here, just defend me, etc.), and so on. Over time, though, that slowly morphed into what we have now.

All this is to say, I doubt we'll get a pet class. We already had one and they took it away.