You continue to get software updates on those devices forever or until the distro ceases to exist. The lifecycle of a distro release is about how long you can

You continue to get software updates on those devices forever or until the distro ceases to exist. The lifecycle of a distro release is about how long you can get security updates without feature updates. But when a release goes EOL, you just... have another update, but this time it will include new feature releases of applications and operating system components as well as the usual security fixes. You also don't really need an LTS for this. In the past I've run installations of Linux for much longer than 5 years on distros that don't do any kind of LTS releases at all.