No matter what happens this is an extremely exciting off season for the Celtics. Most fans outside of GSW have nothing to really look forward to for next year(s). The Cavs fans have no clue how their team can get better to beat GSW because they are in cap hell. San Antonio Fans have some optimism because their team played well before Leonard went down. There are also rumors of CP3 considering them but they have zero cap room and do not have a high draft pick.
Now to the Celtics. They have the number 1 pick in the draft and will most likely pick potential franchise player Markelle Fultz. They have the ability to sign a max free agent. They also have pieces in Bradley, Smart and Crowder that are attractive to other teams to improve via trade. That's a triple threat of excitement that no other team can match.
Imagine picking Fultz and Danny trading future assets for a player that slips that he has ranked high (Giles?).
FA we sign Gordon Hayward. Fill our roster with some vets who can't sign with Cleveland or GSW that want to win.
Trade we move a few excess player(s) for a big (Sign and trade for Jam Green. Tobias Harris, Kyle O'Quinn, Derrick Favors or Dieng)
No matter how far away we are from beating Cleveland or GSW the Celtics are the only team who can improve to the point where they can come close in the short term and be the next GSW in the long term. If I was any other fan in the NBA I would not be this excited.