I'd really consider an Ellis-for-Johnson deal, but I'd have to dump Butler for a pick first. Taking on Johnson basically means that I'd be shopping out of the bargain bin for the rest of the draft.
Ouch, yeah. Without moving Butler, you'd have less than $5 million to round out the roster.
Yeah, I am not sure that is a good trade for Washington.
I don't think they get enough out of JJ with him being third in the pecking order behind Parker and Pau to make that extra salary worth taking on.
I would do the Deng trade though. A lower usage (offensively) guy who can make a larger impact as a defender and rebounder. I think he'd be a great fit in Washington. Give them real physical and mental toughness.