Like, I think, everyone else here- I'm desperately hoping that Ady will land the ZM role. ZM's probably my favorite JY character (with a little competition from Hong Qi Gong and Dong Xie) and after watching Chinese Paladine, I'm convinced Ady will be a great ZM! As a second choice I would suggest that Michelle Ye is great at woman-disguised-as-a-man roles, and she certainly impressed me in World's Finest (though I would be a little afraid that ZM comes across as too comic, since Michelle is probably stronger at comic than dramatic characters.)
I also agree that HuGe would be a great ZWJ, though that's probably asking for too much. I'd settle for either Wallace Chung- who I think did the agonizing-over-the-choice-between-women thing great in Secret History of Kang Xi- or perhaps Jason Wu- who I think would make this version of HSDS the most wuxia-oriented one. I've always thought that ZWJ is not a very acting-challenging role- he's a little bland compared to the women in HSDS, so why not cast a great martial artist in the role who can be adorable and yet dramatic (think Wudang master)?
Zhi Ruo is an interesting character- and though I'm much more neutral here than for the ZM and ZWJ casting- I would root for Chu Ja-Hyun in the role. I think she pulled off a great woman with clear gentle-and-sweet as well as evil-and-vengence-obsessed sides to her in the latest Chu Liu Xiang. She'll give Zhirou a sort of grace and self-possession that the character has lacked recently- I think its harsh to make Zhirou a parody of jealousy and fear (of her shi fu), we need a dignity for her character that would make it clear why Wuji came so close to loving her. In the last chapter of the book ZWJ characterized his feelings for Zhi Ruo as "respect", for his cousin "gratitude", for Xiao Zhao "pity/affection" and, of course, for ZM "bone piercing love"
Pardon my rough translation. The point being you want a Zhirou you can respect!
I think Li Qian would make a good Xiao Zhao- she's the perfectly petite and girlish actress who has great emotional range- and XZ is supposed to the youngest of the girls. We also already know she can be great at farewell scenes (think the ending for Twin of Brothers)- which would be super when it comes to the parting scene with ZWJ (recall the '86 version with Maggie Siu's fantastic parting from Tony Leung... makes me shiver just to remember it!)
For Qing Shu, I want the actor who was Gao Ming (bad guy) in Wing Chun- I guess I've just seen that, and am impressed by his 'character-warping' in there but still coming out with one shining redeeming trait (in that case love for his sister, in the case of Qing Shu some sort of final sacrifice for his father).
I think the other juicy roles to be had are for Zhang CuiShan and Ying Susu, as well as the Da Shi Shu (oldest WuDang disciple). For me personally, I'll never find the equal of Simon Yam and Carol Cheng again, but I'd like to suggest that some more established actors/actress would go for doing a short few weeks of shooting as ZCS and YSS. So, I'll be ambitious and put Vincent Jiao or Vincent Zhao as my favourites for CuiShan. Both look awesome in ancient costume and have done many impressive 'heroic' roles (I think they have the "dai hup" look- as a precedent, Vincent Jiao was great as Golden Snake Warrior in the recent Sword Stained with Royal Blood, and Vincent Zhao needs no introduction in the world of Wuxia). YSS- hmm... oddly I can't think offhand of established actresses I'd like for YSS. Perhaps actresses who have been great ZM's in the past? Like Gigi Lai (I like her ability to give a spark of evil to very sympathetic characters) or Alyssa Chia (she has the advantage of having starred with both Vincent Jiao and Vincent Zhao to great results!).
Right, enough chatter for now- what do you guys think? Perhaps if we can come up with a consensus dream team we can send the director an email plea?