About Gen Wikipedia says: He was a master assassin and friend of Chun-Li's father; he briefly trained her in her youth. However, he was forced to kill another assassin in front of the young girl, and blamed himself for what he saw as the violent path her life had taken since then. He swore never to assassinate again, and instead settled down in Hong Kong, opening his Genhanten restaurant and continuing to perfect his fighting skills, using them on Shadaloo punks whenever possible. Gen's Ansatsuken incorporated various Kung fu styles, such as Mantis, Crane, Bear, and Tiger. He has refined his strikes to target an adversary's vital parts to deliver quick, deadly blows. Gen entered the first World Warrior tournament alongside his friend Lee, hoping to find a worthy opponent. Dissatisfied, he returned to Hong Kong. Gen then took on the responsibility of raising Lees nephews, Yang and Yun Lee, and trained them in martial arts.
Sometime during the tournament Gen discovered he had developed leukemia and had to withdraw from the tournament. Not wanting to die on a death bed he started to search for fighters to give him a "deathmatch". The only opponent Gen had ever considered to be truly worthy of one was Akuma. When the two fought, however, Gen withstood Akuma's most brutal technique, the Shun Goku Satsu, by emptying his own heart and mind. He then struck back with his Zan'ei shadow fist attack, but Akuma was also unaffected (When Gen encounters Akuma during Street Fighter Alpha 3, the match begins with a reenactment of this battle). After a grueling match Akuma was in position to deliver a fatal blow but he left after discovering Gen had leukemia. Disappointed that he did not get his deathmatch, Gen went on a search to find Akuma. Once Gen tracked Akuma down they battled once more, the results of which are unclear, but either he died fighting Akuma or died after the fight as he has not been in the continuity since.
So Shou as GEN, hey?
I think there's some truth in this. Why? Firstly, Yune's name is no longer listed as part of the official production blog for the film that kicked off this week - everyone else in the cast is listed there; Kristin Kreuk, Chris Klein, Michael Clarke Duncan, Vega, and so on - and secondly, at the bottom of that same blog, the webmaster notes that "One [role] that’s not mentioned in the cast breakdown but one who’s surely an integral part of the film" has not been mentioned on the site yet. "And so now, for your first exclusive scoop, allow me to present you faithful readers with some brand spankin’ new casting you’re surely not aware of. The integral role of GEN will be played by none other than……tune in next week to find out!".
The choice is yours - either wait for the big reveal, or believe this bit of gossip.