Literally the only trade scenario I can come up with that makes even a bit of sense in a Billups/Nash swap is if the Suns are able to nab Jimmer at #13. Then they have a guy who they can sell tickets.
Then perhaps they don't need Nash for that as much and they can do a Nash/Pietrus ($11.7+$5.3=$17M) for Billups ($14.2M)+ $3M Cash. PHO saves like $6M and they have someone to groom both Brooks and Jimmer for another year.
Perhaps PHO would be interested in taking Fields cause they need a shooting guard with Vince Carter leaving.
IMHO No way Knicks take on Warrick or Childress without Lopez coming this way.