I have an idea that can reduce the blockchain size by having address maintenance fees. Each address would have a maintenance fee deducted from it every block.

The maintenance fee could be 25 satoshis per block. This means 3,600 satoshis per day. If you have 0.01 BTC (1 million satoshis) it will last 277 days, so it is not a worry.

These satoshis could be used to pay a block subsidy so in the future when the reward is set to get lower and lower, there is still an incentive for miners to mine.