In some perspective of others, transaction fees can provide the circulation of btc even btc will all mined. They need to rely on transaction fees to continuously sustain the functions of the operations. The most directly pretentious in this matter are the Bitcoin Miner themselves, not unless the code of behavior of btc will revolutionize which someone manages to add more btc. Year 2140 is still too long, but I believe in others perspective that btc is still regulated after the 2140, because in this present time we see the excellent effect of btc in trading and exchanges. We know that year btc will also evolved, and that is something we should observe, or maybe by our children in the future.