Well, at least for me, I can activate Siri and voice dial via my Garmin Nuvi all through voice commands to the Nuvi. When Siri is working I don't have to touch my phone at all.
And I am not talking about texting, tweeting, etc. I am a physician and at times absolutely need to answer a phone call while in my car.
As far as Apple "covering" themselves, I'm sure they have. However, the question still arises that they are selling a cell phone with the claim of bluetooth connectivity. When Siri "goes down" the bluetooth connectivity is useless for voice dialing. It shouldn't be impossible to design the OS to automatically switch to the older voice command when Siri stops functioning. At the very least Apple should inform the end user that if he/she is using Siri the ability to control the phone via bluetooth may be lost.
I guess for the time being the thing to do is turn Siri off and use only the older system.
And I remember the "good old days" when I would have to try and find a pay phone if my pager went off ;-(