Jin Yong retired from writing wuxia novels. But what if one day, you manage to convince JY (or Gu Long or whichever wuxia novelist) to hand over the rights to make a 'wai zhuan' [外传], or 'gaiden'. What would you want it to be about?
You can make a film, anime, serial or movie. Whatever. But it must be a story that runs parallel to the events in existing canon. It can borrow characters and plot elements from existing canon, but must try not to alter or contradict them. An example of what I'm talking about is Ashes of Time, the movie starring Leslie Cheung, Tony Leung etc.
Personally, I'd film:
1) Sword Demon [剑魔] - Movie
Chronicles the story of Dugu Qiubai. Starts with a simple beginning and goes on to describe how he became the Sword Demon. Could include a story where the 'righteous person' he injured was his lover, or brother, or best friend. Maybe thats why he got all depressed and took on that title (okok I'm trying my best not to be cheesy...)
The grand finale would be a battle against the 'righteous person'.
2) The 16 years [十六年之别]- Series
Describes the 16 years YG spent while waiting for XLN. Probably starts after he leaves with the Condor and ends at the point where Guo Xiang hears of his deeds at the inn.
Special guest star would be XLN. She appears in flashbacks and other cheesy romantic moments.
3) Jian Zong. Qi Zong [剑宗。气宗] - Series
Describes the events leading to splitting of Huashan into Sword and Qi schools. Main character could be Feng Qingyang. Definitely include how he came to learn Dugu 9Jian. Maybe throw in how Dongfang Bubai imprisoned Ren Woxing and usurped control as a subplot.
One big battle to include would be the 10 Elders attacking all the 5 Mountain Sect elders at Huashan.