This'll probably be ignored, but I'll put it out there anyway. I'd like the ability to mod my Kaithe in the Origin System. Not for Duviri, but for Open World missions, it would be nice to have buffs for my Kaithe available. Here's some ideas I thought of to make this work:
Firstly, mods could be given through Kaithe races that are not part of the story for Duviri. Maybe a low chance or something, like 15% drop chance. Each time you beat a race, you could get a new Kaithe mod.
Secondly, the effects. Speed buff, faster boost while in air, larger radius or just harder slam on the third ability could all be used, along with some conditional mods. Maybe if you fly straight down on a Kaithe, it does a little shockwave on enemies or something similar. I personally like the idea from K-Drives of the fire trail, but I'm not sure how you'd activate that on a Kaithe. Maybe coming down from a flight or a roll? Not sure.
Now, of course, you'd need a good way to level a Kaithe if this was implemented, which could be done with K-Drive races or even implementing Kaithe races in the Open World missions, or just by killing enemies on the Kaithe, treating the affinity gain as like a Warframe, getting half the affinity from kills you get on it.
I don't know, it's just an idea, but one I would like to see. :)