I don't think his contract is justified given his net production (#'s - boneheaded plays), and I don't want him signed or paid here as some prospective one of whatever next "Big Three". The C's will finally have real room under the salary cap next summer if they don't clog it up with so-so players.
If they're keeping Rondo, they'll have some room, probably around $12 million depending where the salary cap winds up, and where they select in the draft. That's decent money, but it's not going to get the superstar you're probably hoping for. Also, this is assuming that Jeff Green opts out and the C's let him walk, and they don't keep any of their currently non-guaranteed contracts (Pressey, Bogans, Johnson, Babb, Faverani), but do pick up the options of all their guys on rookie deals (Sullinger, Olynyk, Zeller).
Not trying to comment on the viability of Smith or not -- just trying to get out ahead of the Celticsblog urban legend that we will have superstar cap room without making some sort of significant move (namely moving Wallace for no 2015 salary.)