1. Coins haven't been spent doesn't mean it's lost (even though some of them are), maybe the owner simply hold the bitcoin for long-term investment.
2. Why would we eliminate satoshi's stats or force satoshi to move the bitcoin? It's contradiction with bitcoin goal.
3. It would take some computational power just to find unspent coins and add it for future circulation
4. I don't see the connection between unspent coins become mined after few years and limiting block size/allowing much more tx/second.
5. I don't think it's good scaling idea since your idea require more computational power and more time to develop/test the idea without much result. Even change max bitcoin supply or add "annual return" feature is slightly better idea.

CMIIW.