Best answer by Airgetlam
If you have an Amazon Alexa device already in your home, you can control all of your Sonos speakers right now, using it. You do not have to replace your PLAY:1s with the Sonos One in order to do so.
I happen to have 2 dots and an Echo that I use to control my older PLAY:1s, PLAY:3s and a random PLAY:5 gen 1. No extra Sonos purchase necessary.