Kurt Shintaku's Blog

The retirement of Skype for Business Online does not impact Skype for Business Server (on-prem) functionality itself.  Per our documentation:

• Skype for Business Online retirement
  “The Skype consumer service and Skype for Business Server are not affected by the retirement of Skype for Business Online.”
  https://docs.microsoft.com/en-us/microsoftteams/skype-for-business-online-retirement#what-does-this-mean-for-skype-for-business-customers 
• FAQ — Upgrading from Skype for Business to Microsoft Teams
  “The retirement of Skype for Business Online doesn’t impact users homed on-premises.”
  https://docs.microsoft.com/en-us/MicrosoftTeams/faq-journey#do-on-premises-skype-for-business-server-customers-need-to-upgrade-to-microsoft-teams-when-skype-for-business-online-retires

IMPACT ON TANGENTIAL RESOURCES
Skype for Business Online’s retirement however will have the following impact to resources often used by Skype for Business Server:

1. Skype Meeting Broadcast retires
   Skype Meeting Broadcast retires at the same time as Skype for Business online, so this service will no longer be available to Skype for Business Server users.
   https://docs.microsoft.com/en-us/MicrosoftTeams/faq-journey#is-skype-meeting-broadcast-going-to-retire-at-the-same-time-as-skype-for-business-online
2. Skype for Business Online PowerShell module/Connection point retired
   The Skype for Business Online PowerShell module & connection point are retired and will fail.  If used, the Teams PowerShell Module instead needs to be installed on your Skype for Business Server Front End servers.
   https://techcommunity.microsoft.com/t5/microsoft-teams/skype-for-business-online-connector-retires-in-february-2021/m-p/2005963