Isn’t that what SonosNet is, in effect? Wire one speaker (or a Boost) to your router and run the rest wireless. 

Sonos has been a mesh system from launch in 2005, way ahead of its time.  As @nik9669a has said, it requires one Sonos device to be connected by cable to the WiFi network,  This is so that data can flow between the WiFi and the SonosNet mesh.

Think OP means to use the Sonos mesh as wifi access points for other devices.

This sort of used to be a thing right? But they deleted the option for android devices to join the mesh IIRC. The Sonos mesh is perfect for audio but it is slow for things like streaming video as far as I understand. 

Ah, I see. I expect that might require a change in the networking components inside many Sonos devices, in order to be able to carry such an extra load of traffic which they’re not currently designed for.  Feasible, over a long period of time, if they were to replace components in current devices immediately, but would cause a schism in owners of current devices, since Sonos speakers seem to last a long time. And it would change the focus of Sonos as a music player to a network device company. 

All good and useful observations from previous contributors.  Also, in SonosNet mode you can wire other devices to the Ethernet ports of Sonos devices to allow them to connect to your LAN.  So Sonos can be used to extend a network in this sense.

BuT @Bumper is correct that SonosNet is great for reliable audio transport but is not designed to work with bandwidth heavy loads for streaming movies.

If the OP is hoping for Sonos to take over all the networking then that is never going to happen.  Nothing wrong with wishing, though...