They are thinking of creating a new job unique to ffxiv so lets give them some ideas!

[Claire_Pendragon]

I would like to see them add a pet job for melee dps (puppetmaster?) and tank. Then every role in the game would have a pet variant.

Though most "Pet Tank" idea seem to be "Have the pet tank", and as much as I'd like to see that, honestly think the pet would have to act as support to the player tanking instead, due to a lot of the limitations.

Probably something like the BST doesnt have tank stances, but instead, the pet toggles between doing dmg, or putting a tether on the tank to heal them and raise their enmity.
(And for invuln, maybe have the pet equal you in threat, and then stay ahead of you in hate, taking 75% less dmg until dead, unable to be healed, and reseting their summon action.)