It wouldn't be about making a newer, more up to date version for younger audiences anyway!!!! It would be about making money for hollywood, as per usual.
Plus if you know anything about the Owners, Handmade Films, then you would know how much of a dick Denis O'Brien was to the completion of this film. It was lucky ever to be made thanks to his lack of funds, and only thanks to Bruce Robinsons large (mainly empty) pockets for spare funding. My bet is that he's an uptight git that wouldn't release the rights to Withnail And I anyway.
You've really caused a shit storm here "Withoutnail"