"Now" is the key there. It wasn't $20 when it came out. Neither was the original release. It's a given that junkies are going to pay any amount of money they have to so they can get their fix and smile while they do it, but I'd imagine the average gamer has the advantage of not being too attached to say no.
Has Capcom ever done a season pass type of thing for their games? They of all companies should. Buy the original release and pre pay for the inevitable milking ahead of time with a slight discount.
All the Resident Evils as far as I know have offered nothing whatsoever.