An example of such a change (overdue in my view) would be to determine that every wallet needs a transaction at least every 2 years. Then all blocks older than 2 years are pruned from the blockchain. This would also open the possibility to replenish lost bitcoins.
I don't think that could be easily implemented; unless you put a 2 yr expiration date on each unspent output. But then a wallet receiving only incoming funds would expire, and a wallet that never went under 25% of it's balance in the last 2 years may see those 25% dissapear.
The network has no way to know whether the funds are sent to a particular wallet or not. Wallets may (and do) contain multiple addresses. Some transactions are not sent to a particular address, but may only be spend with specific conditions, such as providing 2 out of 3 signatures...
But the network actually -does- incite users to not let old outputs go unspent for a long time. The current network rules may waive fees if the transaction consumes an old enough output.