Holy crap, I forgot about this, probably the highlight of my day when I saw the thread title. I thoroughly enjoyed david production's Urusei Yatsura and after watching the last episode, I pretty much wished for dp to do a Ranma remake too but I didn't bother to try searching for news until a few weeks ago!
The two differences I've noticed in the cast so far from the video are the two dads - Panda Dad is now voiced by Cho (Brook) and Tendo Dad is now voiced by Akio Otsuka (Blackbeard). I feared that there was a chance that some of the older folks wouldn't be able to reprise their roles, but it seems Genma's previous voice (Kenichi Ogata) is listed to be the narrator at least. The passing of some VAs in the Detective Conan anime recently was tough to swallow and looking up Genma/Agasa he's currently 82 years old.
So far it looks real clean, and it's MAPPA. Here's hoping for a great adaptation like Urusei Yatsura.
Ranma was Kappei Yamaguchi's breakout role wasn't it? Must be a crazy feeling to be able to revisit it after all this time!!