"Oh, jeez, Alexa, just do it already without asking me stupid follow-on questions!"

One of the reasons I'm less sanguine about voice as an uber-interface. I'm not sure you can square the circle between a rich and capable interface and one that isn't interrogating you like that. Computer screens can pop up arbitrarily large amounts of data on the screen (entire EULAs) to be dismissed almost for free. The serial nature of speech is going to be a big challenge for most people. (There are, of course, those who use it all the time as their interface. Perhaps a few will even read this post. But I'd submit their usage doesn't end up looking or sounding much like the Star Trek ideal.)