Will voice services like Amazon's Alexa really rise as fast as predicted?

Amazon’s Alexa assistant is booming. Around 5m are installed in America alone. And Alexa has around 7,000 skills.
This is a great strategic move for taking on Google and Facebook, which makes Amazon the centre of a new digital ecosystem. An argument made brilliantly by Ben Thompson last week.
Alongside Alexa, Baidu and Google have rapidly improving voice recognition.
So people are using voice services a lot more than they did. But is there a limit on how big they can get?
Yes.
There are a