I very much doubt that speaking is slower than typing, given that basically only stenographers can transcribe things in real time, and that's by using special technique.

Try typing for 4h and talking for 4h.

Leaving aside the problem that you can no longer share a space if you interact by talking.

Talking is still faster, and I can do it while my hands and eyes are occupied, so I definitely don't see typing ever being the preferred interface. You'd never type to interact with an assistant while driving.