Best case scenario in my opinion.....if Ainge can pull this off it would be incredible.
If during the off season we can sign Gordan Hayward, trade for Drummond, keep the 2017 Nets' pick and somehow land the #1 spot drafting Markelle Fultz, and to some extent keep the core of our current team intact with IT, Crowder, Bradley, Smart, and Jaylen.
This I feel would give the Celtics the most promise and potential to make it to the finals ASAP and be a legit contender for a very long time. High character guys, fill the rebounding void with Drummond, respark the Butler chemistry with Stevens and Hayward, and have an All-Star caliber PG to replace IT as he ages.
There's probably a less than 10% chance of all of this happening and falling into place, but a die hard Celtics fan can dream.....