I would love to see a nearly thousand year old Dax go all Gunnery Sgt Hartman channeling the disappointment of every WW2 Veteran who lived to see current year. Just full old man rage let loose.
I could just see it, Dax giving a special guest lecture to Starfleet students. Spying the half-Klingon, half-Jem'Hadar. The slow pan as their head turns to Gayden and the knife hand comes up and the lecture begins with "Every second you let that abomination live, you dishonor your House and the Empire. I did not fight four wars against the Dominion so you could just let one walk in here and sully an XXXL Starfleet uniform." Head then pans to autistic hologram. "Alright, whoever programs these things should be ashamed of themselves. Find out who made that, and then tell them to make it hot...you know what make it me when I was Ezri Dax, circa end of the First Dominion War and send it to my quarters. After you all hear what I am about to say. You're all gonna think I can go fuck myself and you know what...I'm gonna get all Tom Paris in that."