I kinda feel like they could remove Egi as pets completely... Would completely destroy any comparison to XI, just replace the Summon skills with their respective Egi abilities... Rework all the existing skills as I've described, so each one corresponds to a specific Egi, then have Enkindle function like Kassatsu on select abilities... Instead of Summon I, you have Garuda-Egi in the form of Contagion, while Summon III becomes Flaming Crush. An Enkindled Flaming Crush is just straight up Inferno, even opens the door for more Enkindles; Enkindled "Shadow Flare" could be a joke Zantetsuken...
IDK, more work than it's worth IMO, you'd need to completely rebalance the entire Job to make up for the lost pet damage, but at this point the Egi just feel really lackluster and pointless... You have Contagion or soloability which pales in comparison to Warrior or Scholar... If trash packs in dungeons were scaled to die quicker, Ifrit-Egi and Radiant Shield might be more potent than Contagion, but I don't think that's the world we live in, Contagion + Bane > anything else... Rather than a fourth pet, I'd say just rebalance what we currently have... I think Machinist works a lot better as a pet Job currently, both pets have a clearly defined purpose, I'd actually quite like to see them get a Knight type autoturret, which upon Promotion provides damage mitigation, with Hypercharge applying a Drain Samba style effect for a sort of Regen effect... Summoner could work on a similar principle... The main problem is Bane/Contagion... It makes Summon I both the best single target pet and AoE pet... I'd say drop Tri-Bind, make Contagion the Lv40 skill, give Summon I something else and give the current three pets clearly defined roles as single target focused, AoE focused, and support/tank focused. Perhaps have Summon IIs Enkindle be an Asylum style effect, rather than a second Shadow Flare... That's useful for solo and potentially has a small niche in party content... Could change Earthen Ward too, and I guess Landslide? Though the other two skills are pretty much required for him to hold hate solo...
Although... As I said, not fond of cross-class skills for the most part... Summoner having Quelling Strike isn't right IMO... I want the same effect done in a way that is unique to Summoner... Shadewalker (wow, such unique), but limited to my pet, achieves the exact same thing as Quelling Strike, but in a way that fits Summoner, and potentially frees up Summon II to work solo (any of them, really) with less enmity skills... He can still be a tank, but you'd free up some room for more support oriented skills that could benefit people in grouped content. Kinda wish Sustain was just a stance that constantly drained MP to heal/channel your enmity to your pet... That 10s duration is just irritating...