I've been thinking lately about a way to address this: get a "phone" with no cell hardware, and pair it with a cellular/WiFi bridge such as MiFi. Get internet-based replacement services for voice calls and texts. Now you have one less undocumented interface or super-privileged CPU to worry about.

There's a lot of practicality questions in terms of battery life, expense, convenience to carry around, but for certain security scenarios it seems like a step forward.