I know this is getting ahead of things, but I am thinking about the historical house/mansion that he so lovingly restored, and the grounds that are so impeccably kept. Apparently he held multiple charity events at his home, including for the opera and other cultural organizations. I would love to see a local philanthropist purchase the home from his family (if he left the home to his family if he had a will, or if he didn't then it would go to his family automatically, I believe). And turn it into the Devon Hoover Museum or something similar in his name (or the Devon Hoover Center for the Arts, or something similar).
Gardening groups could also maintain it, the fountains, plants, etc. This assumes the family will not want to keep it, I suppose it depends on their finances. But if they do decide to sell it, then I hope it is purchased by a wealthy philanthropist or philanthropic organization. And with a family member or two serving on the board to ensure it stays true to his memory. Just some thoughts on the future of this wonderful property that Dr. Hoover so lovingly restored and poured so much of himself into.
Edited to add - So many I think would love to see a monument/place like this in his memory and generations would be able to learn about this unique soul at the Hoover House in Detroit, Michigan.