If I were to guess, Vesely and Ariza get traded for one player. Childress does end up a Wizard, because IMO they're not figuring on re-signing Trevor Ariza. Besides, they drafted Otto Porter to be the SF of the future. I could be very wrong but I could see Ariza being out and Childress being in, for better or worse.
Why would Childress come to Washington unless he thought he had a decent shot to stick? If he sticks, someone else goes. Maybe he knows Dan Grunfeld and Ernie well from Stanford days and he feels he can stick. Only happens if Ariza goes IMO.
ONE MORE THING: Childress played with Harrington on the Hawks years back. Harrington played with Nene. Chemistry, experience, and Randy Wittman seeming to prefer veterans points to Childress having a decent shot if he can play at all well IMO.