I actually think they'd have a ton of optimism if instead of trying to balance out between contending now while developing their young guys they can just go full on development mode and really maximise Tatum and Brown's potential, and I think a lot of Celtics fans wouldn't care too much about Irving's departure after the season he's had, even though he's clearly a star caliber player.
More interesting thing about the Celtics offseason to me is whether Horford stays or not as I think Kyrie has been out the door since like January. Horford's got a $30 mil player option this year but if he declines that to chase another deal I don't know whether the Celtics pay him, or what other teams would pay him close to that money. But I could see Horford taking a paycut if it means he's playing on a contending team, and if he doesn't think the Celtics will contend next season if Kyrie goes then I'm curious to know if he'd bolt too and take a $5 - $10 mil paycut to play for an elite team.