At first, I rejected this possibility out of hand. I want to see Ray and KG retire in green.
However, after thinking on it a bit more, a lot depends on 1) what the new CBA looks like and 2) what the Celtics are hearing through back channels.
Right now, if we added Smith and otherwise cleared our salary cap (getting rid of Bradley and our #1 this year, and not signing any multi-year free agents), we'd have about $41 million committed going into the summer of 2012. If the cap goes up to around $60 million, that's almost enough to sign a max free agent like Dwight Howard. If Danny was hearing that Howard would join a core of Rondo + Smith, I think we'd have to do it.
However, without guarantees about both the CBA and Howard's willingness to join the Celtics, I don't think you can make this move. Josh Smith isn't good enough to cut into our cap room for.