A couple of points.
Once Howard is signed, if signed here getting everyone else that Scooby and some of you others have said can be here will be very tough.
Pierce
Rondo
Bradley
Moore
Johnson
1st rounder
1st rounder
Will make up for about $34 million in salary against a $58 million cap. Bass has a cap hold of nearly $9 million. Jeff Green has a cap hold of $11 million. KG and Ray's cap holds are huge.
To assure being able to fit Howard under the cap in a max contract, every single free agent the Celtics have will need to be renounced meaning we no longer have their Bird rights and all we can offer them is the money available under the cap and then once we reach the cap that new exception the CBA put in this year.
That means $34 million for the above players and about $17 million for Howard and then cap holds of about another $2 million to cover the empty slots yet to be filled.
That leaves $5 million in cap space needed to attempt to bring back Bass(probably looking at $6-8 million starting over 4 years), Green(probably looking at least a $3-6 million make do one year prove it to me contract after such a serious situation), KG, Ray, Stiemsma, Pietrus, Wilcox etc.
In other words, don't expect Bass back. Green maybe but that could be doubtful. KG and Ray will basically have to take vet minimum contracts or wait for the over the cap exception to kick in and see who gets that whole thing.
I just don't see most of these players returning if Howard signs.