I believe there is software out there that will convert speech into text. Its not coh related and it may not even work with it but it exists... somewhere.
I doubt they will do it. With third party voice chat systems, teamspeak, ventrilo, etc, and with many speaking against voice chat, its not viable in a business sense. Besides, updates are things that have been qued up and worked on for months, if not years before we even know about it.
Also, I don't think this is the right section. You want player suggestions or ideas or whatever that section is. This is more for displaying media, player made videos, comics, edits to demo files. Pretty much to show work players have made or help each other learn or do other stuff. Not a suggestion area.
Still, would definately be cool option if ever. 
Need help making your own CoH comics or read other's comics at cohcomicindex.com
www.jkcomics.com for Justice-Knights comics series and more!
Storylines:
Introductions, Obey,
Comming from DDO and LOTRO with the built in team chat, I miss that. It was great for PUGs but for Supergroups, Ventrillo or Teamspeak works better. Many people used both. In-game chat for teams (Z) and (X) for kinships (LOTRO's version of Supergroup).
I have lost all ability to type and play at the same time.
But then again, I enjoy listening to Cape Radio while playing, something that does not exist in LOTRO. It REALLY adds to the feel of Paragon City being a real place.
the trick here is that while Ventrilo and Teamspeak are free for noncommercial use, most voice chat has hefty license fees associated with it for commercial integration.
And... well... it was announced almost two years ago that they were going to do it. I figured that TR's demise and the NCSoft shake-up killed the idea.
That... and... well... many of the current player base gave a resounding "meh." Voice chat is nice for a new game, but many of us dread the idea of the xbox-syndrome invading our favorite game- squeaky-voiced prepubescent profanity-spewers that are all the more annoying because they THINK they're badass. At least with guild/faction voice chat, you have some selection in who you give out the server info to...
Yes that's an unfair judgement... but one from experiences so bad that just memories of them are like fingernails on a chalkboard.
This is for the development team....
I was thinking maybe some players (like myself) would like to be able to attack enemies and create strategies for game play without having to type in the chat box everytime. Im simply suggesting that maybe the developement team would make use of a microphone in the next update. Eventhough it is not necessary it can help player like myself play without having to type in a chat box.