That is the perfect place for voice texting. The audio texting idea is pretty useless and gimmicky, voice texting is a MUCH more important and useful feature as big of an issue as texting and driving is. I have always felt this should be a completely separate feature from Siri as I hate the awful placement of the Siri mic as it clutters the keyboard and cuts the numbers key in half making it almost impossible to hit, let alone when driving. Texting while driving is incredibly dangerous, probably among the most unsafe things you can be doing while driving. Apple loves to stand out and be unique and lead the herd, this would be a great opportunity for them to do some image crafting as well. Creating a separate "voice texting" function and putting it in a visible easy to reach spot would draw much more attention to it. I wasn't even aware it existed and actually worked for a while as Siri had a number of problems starting out and they really didn't advertise that feature of it heavily. I never bothered setting it up for this reason in addition to the poor implementation and cumbersome location of the Siri mic.