What percentage of CPU power do you think will be mining bitcoin 5 days before vs 5 days after all of the coins have been mined?

If you think the amount will be roughly equal, then you are predicting that transactions that end up in blocks will need to voluntarily contribute an amount equivalent to the block reward in order for the system to continue functioning. This seems unlikely to me.

Transactions already include fees today. The minting rate of new bitcoins goes down over time, so when minting finally ends, it won't be a sudden change to the mining rewards. It's expected that the mining reward will be mostly transaction fees by the end, so the mining reward will only be a little affected by the minting being stopped.

> the minting rate of new bitcoins goes down over time

Isn’t the difficulty level calibrated based on 10 mins per block? I don’t see how your statement above can be true. Seems like it goes from one reward every 10 mins (on average) to 0 rewards as soon as the last one is mined.

There's a block every 10 minutes, but the number of bitcoins minted per block goes down over time. It used to be that 50 bitcoins were minted every block, but currently only 12.5 are minted each block. The amount minted halves every four years. (Personally, I think it's too extreme that it instantly goes from x to x/2 in one block. The mining rate generally dips a bit for a while when this happens. I think it would have been better for the minting to decrease in a much smoother way.)

Thanks for the clarification. Going to back-fill and update the rest of the logical conclusions I had drawn :)