“Qualitatively, Amazon’s position is more secure than the numbers would indicate.”
I beg to differ. I believe Apple has a much more secured position than Amazon in the long run, given how Siri is already integrated in iOs mobile devices and macOS based desktops. So far, has Apple capitalized on this advantage? Nope. Are they gonna? Most likely, given the fact that they always wait for everyone to show their projects in high school science fair and then they roll out their better comprehensive showcase.
If Apple does not launch a voice based home automation product in late 2017 or early 2018 then it might be too late.
Apple's true competitor in this domain can only be Google with its staggering command on Android ecosystem. Microsoft effort is limited to Windows based PCs and even they might have a better advantage than Amazon.
Amazon has mainstreamed a voice tech. They have done it well and made a point that this is the way of the future. Now the second part of the problem is to integrate already existing daily use computational devices with this "voice-tech". Amazon literally has none, no mobile and no desktops/laptops/tablets.