I think 5 years.

I suspect the business model that is most likely to work is an extension of the current one.

Larger multiplexes with more screens, when you go to the cinema you have a wide choice of movies to see.

Movies would no longer drop out of the cinema within a week or two.

In this controlled environment it is easier for the cinemas to prevent copying.

Only after a long cinema run would the film be released on DVD, after which point the copyright expires and you can copy to your hearts content.

I can even see this business model perhaps working for music as well.