I'm afraid that like CDR trades, this is one discussion that should not have been done in public. Blue Note has read this thread and has decided to withdraw the entire set of March 1st RVG reissues, as well has cancelled plans for the Summer RVGs and the Fall Conns.
Did he actually leave ECM?
I don't think ECM has exclusive contracts, but yes, Holland's Quintet will be recording on his new label.
He may still do other projects for them as a co-leader (e.g., "Gateway").
And Carla Bley does a very Carla-esque version on her new release:
Carla Bley - The Lost Chords (Watt)
— with Andy Sheppard, Steve Swallow and Billy Drummond