I didn't say you could have 4 out at once... that's why I think they're going to be single-animation moves, otherwise there would be nothing stopping them from staying out.

Arcanists can use Carbuncle which is a permanent summon, but summoners won't be able to access him, so I think that's probably their way of stopping the job becoming too over-powered. But then again, if they do add multiple jobs per class then maybe there will be a job that can utilise more permanent pets, like in XI. If they do that though I think they'll more likely be elementals than actual Primals