I think 50 years would be a reasonable first step. I think something more like 20 or 30 years would be more objectively reasonable (if you believed in the original intent of copyright, and not just for companies to be able to make as much money as possible out of any content), but potentially a bridge too far for the foreseeable future.

The main thing I'd like to see would be to get rid of any silly "life plus x years" terms.