On April 1st, 1956, the S-A Board of Directors approved the discontinuation of AW production and manufacturing cutover to the new SW hub.
https://www.sheldonbrown.com/sw.html
At the request of dealers and OEMs, the AW would be returned to production in 1958.
Fun fact: Drum brake and Dynohub versions of the new SW were prototyped but never manufactured. The AW gear mechanism stayed in continuous production in the AB (drum brake) and the AG (Dynohub) versions.