Earlier quoted context omitted.
I would require copyright holders to renew their copyright. 5 years for free, then $1 for the 6th year, $2 for the 7th, $4 for the 8th, $8 for the 9th, $1m for the 25th, etc.
Not every copyright holder is a massive corporation. Artists produce many pieces per year. That would cost them a lot to keep copyrights.
I think GP's scheme isn't awful honestly; it would have the effect of drastically lowering the practical length of copyright for most works while providing artists with a way to maintain copyright over works that are actually highly successful. (A per-year doubling might be a bit much but I think it's on the right track.)
If the practical effect was that we mostly got back to the original copyright term we had in the US (14 years with the possibility to extend that once), I'd be pretty happy. Maybe start the fees after the 14th year.