I understand any output in blockchain can be left un-redeemed forever. But If we expire all transactions that are more than two years old (specifically after some number of blocks), there are some benefits
- Recycle lost/destroyed bitcoins by giving them back to miners
- Miners will continue to get more transactions and thus more fees
- Number of unspend transactions may become less speeding up verification
- Size of blockchain to keep downloaded can be minimized
- Broken cryptographic hahes/signatures can be made obsolute
- New features can be easily introduced
Are there any alt coins that consider these? What are the advantages of keeping all transactions valid since genesis block?