Version 5.1 on the Sonos speaker firmware makes installation of the company's speakers easier by eliminating the need for the Bridge device or wired connection to a router.
The company describes the speaker setup process as such-- "Start with a Play:1, your smartphone or tablet, and connect to your wifi. Then, simply add your favorite music services like Spotify or Pandora, and start streaming."
Obviously speakers need to be in range of home wifi signals in order to benefit from the simplified setup, meaning a Bridge might still be required for larger and more elaborate setups. Either that or a future Sonos offering called Boost, which promises to provide installers with "enterprise-grade" wireless capabilities once it launches in the coming months.