Yeah, I like the way Ubuntu handles it. Basically, if you come boo-hooing in Issues and you are using an ancient non-LTS version, you'll be asked to install an LTS (or latest) version first. That way you only have to maintain a tiny subset of your releases, and your users are incentivized to use LTS or make sure they are up to date.

You have to support those LTS releases. Their solution is to update everyone to latest and only support that one.