If CON does return, I hope they take steps to not repeat what I consider one of the dumbest flaws of the GBA games: Most girls have less constitution than their male counterparts, and quite a few of them suffer for it. Thankfully, the ones who suffer for it would likely suck regardless, so it isn't too damning, but it's still irksome that Marisa's incredibly slight speed advantage over Joshua is completely nullified by her CON. as a Myrmidon, she gets weighed down by a Killing Edge while he does not. And then as Swordmasters, she gets weighed down by Audhulma, he does not. Basically any sword stronger than Iron will affect her more adversely than him. Neimi and Innes are in a similar boat. Amelia doesn't get any CON from promoting to a Paladin for some reason, and a significant amount less than Franz, Forde, and Kyle would when promoting to a Great Knight.
The most jarring example would be Isadora, one of the most worthless prepromotes I've ever seen. A 20/1 Sain, on average, should have 1-2 less speed than Isadora does when you first get her. Of course, keep in mind a 20/1 Sain will also have 11 CON compared to her 6, and a fair amount more attack. Even a simple Iron Lance has 8 weight, equaling their speed. 20/1 Kent doesn't even need the CON difference to outspeed her, but it certainly helps widen the gap all the more when it comes to wielding anything heavier. Even Lowen will have higher effective speed when it comes to wielding anything heavier than an Iron Lance. Hope you weren't planning on giving her a Javelin, or anything at all, really.