They can just have the carbuncles and old egis being just cosmetic companions.
I think there's a reason why the pet gameplay has escalated into what it is today, and is probably not just some AI adjustment, but actually the foundation of that "sphagetti code" not letting them go all the way through with a proper functional pet AI.
Despite us, or them, either enjoying egis or not, if that's really the case, then it's better to just give the last blow on the pet gameplay, since it's nearly that to begin with...