Dwight is friends with Rondo and Smith. If the rumors that Dwight is leaving are true, maybe Atlanta can sell Dwight on forming a trio with Rondo and Smith in his hometown.
So given that hypothesis, I think a reasonable trade for both teams is
Horford, L. Williams, Teague (S&T 4 yrs, 36-40 million), 2014 1st (lotto protected)
for
Rondo, Lee, Melo/Sullinger, Crawford, Williams, Randolph, White
I believe the numbers should work out depending on where Teague starts.
That would give Boston a very strong roster next year, get the team younger, and pick up an extra first in the 2014 draft.
So Boston would be
PG - Teague, Bradley, Terry
SG - Pierce, Williams, Bradley
SF - Green, Pierce
PF - Horford, Bass, Sullinger or Melo
C - Garnett, Wilcox, Sullinger or Melo
In addition to the 2013 1st and any free agents. That would be a pretty dangerous team if PP and KG could provide anything even remotely close to their primes in the playoffs.