From the numbers I've seen, I don't know how you could add two big salaries without waiving or trading almost everybody else except IT and Horford. Doesn't seem practical. The main selling points are those Nets picks--that's what Indy and Chicago want.
The fact that Ainge did nothing at the trade deadline suggests to me he has a FA already in his pocket this summer. That could be Hayward. He is just biding his time. In contrast, you have the Champion Cavs scurrying around trying to add players. 
Butler and George's salaries aren't that big.
Butler, Mirotic for Bradley, Crowder, Jerekbo, BKN 18, MEM 1st, 3 2017 2nd's
George for Brown, Zeller, Young, BKN 17, BOS 19, LAC 1st
PG - Thomas, Rozier, Jackson
SG - Butler, Smart
SF - George, Green
PF - Horford, Mirotic, Mickey
C - Johnson, Olynyk
3 open roster spots for signing cut players.