DO appears to still be alive
More patents for large Canon DO lenses. The one of note is the 500 f/5.6, a lens that would be a very solid follow-up to the EF 400 f/4 DO IS.
We've seen a lot of these patents in the past, and none of them have ever come to market. It is good to see R&D is still going into DO technology, as I really enjoy the 400 DO.