Yeah, he's either not going to be Wei or it's going to be way rewritten. The entire thrust of the main plot of SD involves young characters scrapping for their pieces. Kind hard to show when your lead is in his 50s.
I would expect this to emulate all the Hong Kong action films that inspired it in the first place. Which means this could be a really fun movie, especially with Donnie Yen as the lead. Man is he old AF to be playing Wei Shen tho