We’ve known this was happening for a long time, and we’ve finally got a date. Skype for Business will be retiring in about two years from today, on July 31st, 2021. The service will no longer be accessible at that time, that means no opening a support ticket to back out of Teams. Two years happens fast, so if you haven’t started your migration, you’re already behind. While Skype and Teams don’t have complete feature parity, the vast majority of it is there, enough that even an old Skype salt like me is comfortable. Get moving!
Official announcement is here: https://techcommunity.microsoft.com/t5/microsoft-teams-blog/skype-for-business-online-to-be-retired-in-2021/ba-p/777833