Switch from AT&T U-Verse to DirectTV Stream

What equipment do I need to return if I cancel U-Verse and switch to DirectTV Stream?  Specifically, do I have to have replace the WiFi Gateway that was provided when I installed AT&T and replace it with a new 3rd party WiFi Gateway?  I plan to retain my AT&T DSL line.  I currently have three AT&T U-Verse Wireless TV Receivers, an AT&T WiFi Gateway and an AT&T U-Verse Wireless Access Point (WAP) that all were provided by AT&T.  My preference would be to only return the three U-Verse Wireless TV Receivers and retain the Gateway and WAP for continued use in my home.  Also, I don't know if the WAP serves any purpose other than to support U-Verse.

Thanks!