The alternate (much more banal) explanation for the current prevalence is 1) a cynical data-grab on the part of companies, and 2) the devices are cheap and novel for consumers. In other words, it's not that they're creating such great value, but that companies have learned to embed their data-vacuums in what amount to toys.
I don’t subscribe to the just a data grab theory, that is incredibly cynical. Also, even a simple device is useful if it’s cheap enough (“Alexa play space unicorn” is really useful for us parents).
Still, that's about all of our progress in 50 years (in production ready, deployed systems). Estimating that we need another fifty years seems fair.
We have to account for accelerating progress, but I'm not sure that's enough to bring us much closer than 50 years away