Who am I kidding? You’re not really going to get ready, but let’s talk about this anyway.
According to Microsoft’s SQL Server support policy, that means from here on out, Microsoft will only deliver security patches, not functional, performance, or stability patches. You can still call Microsoft for help, but if you find a performance issue and they need to build code for a fix, you’ll only be able to get it on the two mainstream supported versions – only SQL Server 2017 and 2019.
Microsoft’s current support policy is that new versions only get mainstream support for 5 years. We still don’t have any public previews of the next version of SQL Server, let alone a 2021 release date. Even if Microsoft released the first public betas tomorrow, and gave us RTM this winter, that means that starting October 2022, we’ll be back to only 2 mainstream support versions: 2019, and whatever vNext is.