I gotta say, now with OKC on the verge of eliminiation, this actually might be a possibility.
I mean I think most GMs would agree that Westbrook is a better player but at what point does OKC not consider the idea of shaking things up if they can't win a title with the 2nd best player in the league in Durant?
What about something like this
Celts get Westbrook, Perry Jones and Hasheem Thabeet
OKC gets Rondo, Jeff Green
Oklahoma City would do a lot better than that if they traded Westbrook on the open market. Some trades I think they could potentially make
with Lakers (during free agency)
Westbrook, Perkins for LAL #1 (whomever they drafted), Nash, Pau (sign and traded - something like 3yrs, 35 million)
with Rockets
Westbrook for Parsons, Asik, Jones, a couple of firsts
with TWolves
Westbrook, Perkins for Pekovic, Rubio, Barea/Moute
with Pelicans
Westbrook for Holiday, Anderson (pending physicals for both)
with Cavs
Westbrook for Irving, filler
I'm sure there are plenty of other realistic trades out there where OKC can move Westbrook and get a much better offer than anything Boston would realistically offer (i.e. I can't see Boston moving both Rondo and the high 1st for Westbrook).