I'd say a big trade involving Rondo is very unlikely.
I think Rondo either stays or leaves during FA for nothing or for pennies on the dollar in a S&T.
I think Ainge will hold onto Rondo until 2015 FA and try to convince him to stay. If Ainge makes a big move, I like the chances of Rondo staying. If Ainge does not, then it gets murky and Rondo could leave during FA with BOS getting little or nothing in return (late first or pair of 2nd rounders or role player youth).