Don't spend too much time worrying about what we could get from Dallas in a Rondo trade. If this source is to be believed over the other source, then there's no substance to those rumors from the other source. That is unless another source tells us that they have more sources to refute the refuting. Or something.
Source: Report of C’s/Mavs Rajon Rondo talks ‘ridiculous’ | Boston Herald
“The Celtics haven’t had any conversations with Dallas about Rondo,” said one source. “That’s ridiculous. There’s no truth to it. What in the world does Dallas have to offer for Rondo?” The second source pointed to the thin state of the Dallas roster. “They’re trying to rebuild around a 37-year-old Dirk Nowitzki,” he said. “They have a lot of old expiring contracts, and that’s about it.”
Also, if you have heard anything about a Knicks rumor, take it from this Knicks blog that "there is no Rondo rumor."