It's been 13 years, do you have any evidence to say DO isn't ready for prime time? It'll take a lens release to show it...
Canon have stuck with DO because they want to, they want to make that square peg fit in out round lenses, and they will spend countless man hours on keeping it going for no other reason than they want to and they patented the heck out of it so they can. Sure in ten years (weren't we saying that thirteen years ago when the 400 came out) when DPP can "adjust" for the aberrations in post it might work, but seriously, who cares? When DO is ready for prime time then bring it to market, I am all for it, in the mean time keep the people who pay the bills happy (us customers) with lenses we want, we need, and we can afford.
I think it is a pretty safe bet that it won't be dramatically different, why? Well the issues it has are at the core of what it is, so it will take a completely different approach, not a Canon strong point, to overcome it, or a different technology like re sampling or a different demosaic algorithm to work around. Something like AA filters and moire, we know what causes it, we know how to have sensors that don't have AA filters and don't cause moire, but we are just not there for a few generations yet.
At this point in time and tech DO is DOA.
Besides I don't want Canon focusing on a lens they make a loss on, and there is no way they have ever made a cent from any DO lens, I want them to make lenses they make profits on then they will have more R&D money and will make even better stuff.
"...DO is DOA"
How do you actually know that!!
If Canon do bring about an improved 400DO it maybe a signal that they have reached the end of the line with weight reductions on the big whites with current designs.
I am sure there would be a big market for a sharp 3kg 500/4DO or a 2kg 300/2.8DO.