Bringing back Rozier is a worthwhile option at the right price if Irving leaves. It doesn't mean we are married to him as the long term starting point guard. Rozier also tends to play under more control as a starter anyways.
The success of next years group, barring a fireworks trade, will ultimately come down to the core of Horford, Tatum, Brown, Hayward, and Smart. For all his inconsistencies and limitations, Rozier can function just fine if those guys play to their potential. Additionaly, Rozier would serve as an outgoing salary in potential trades for a Superstar.
At the end of the day I'm not losing sleep either way. Just don't be surprised if Danny matches an offer in the $10-12 million range.