Old software will continue to work, until some time in the future, when the eLCC server will be switched off, at which point you won’t be able to activate new licences. Even then, existing installations will probably still continue (assuming no other future issues like incompatibility with new OSes.)
The dongle has worked for me for 33 years. Can’t say I’m happy about these changes. Sigh!
Great news, Daniel. Thanks for the changes. I can’t wait to see Dorico 4.