Umm..Well, I do not hold any power here but I can confidently say that won't happen. It's not a bad idea, but everyone has an "about me section" on there profiles, so you can just see there as most people simply put there username changes there instead. One click isn't too much to ask of really.
I know that some people don't use their about me section, but if they can't be bothered to do that why would they be bothered to fill out something on a whole new section? so I doubt this will happen. I mean, you could just ask them.There is know harm done in not knowing if someone has changed name. Plus, recent name changes stay up on the actual "Name rater" for a good amount of time.
Mod's feel free to hide this if you think that the idea isn't too bad I guess...