Mark Oppenheimer's book on Edo Shimano - THE ZEN PREDATOR OF THE UPPER EAST SIDE - which was an e-book - is now posted on-line as a web version - for free. It's abridged somewhat, but not that much. You can read it here:
I have no updates on the state of his organization, but likely it is fading into unsustainable obscurity. It is also likely that Joshu Sasaki's scene is also in a similar situation - entirely do to their institutional blindness and obedience / loyalty to what?