I think that makes too much sense to happen.
It would make sense - Philly could live with Arenas - he wouldn't be in the way of their younger guys and would actually fit into their team. It would also give a chance for Philly to rehabilitate Arenas and get more than they'll get for Brand, who I'm sure will look bad in either system. They could work Jrue, Young, and Favors all into the mix around regardless of who starts. They could also still take Turner and trade Iggy - who probably has pretty good value.
For WAS I like it even more - they get rid of Arenas' baggage before he starts impacting Wall's development and bring in a post guy and all around good guy who should help. For some reason I invision them playing slower pace than Philly, which would help Elton. Again same idea - they can feature Brand and try and get his trade value up.