That is the problem by the next generation! 2140 is too far in our time! We are all dead if the miners will put high transaction fees. I have two assumptions if bitcoin supply will already circulate to our economy, one thing is that it will suffer to a catastrophic event by means of bitcoin's falling down or it will change its system, making it as proof of something than proof of work. Anyways, I never really matters that all. I just wanted to know when does bitcoin circulate its max supply so I gather some information.
It's not that we are all dead there could be a lot of untouched coins in the future that would make bitcoin harder to get and we can't be sure if bitcoin would still be valuable or alive during that time there could be other altcoins dominating the market 100+ years is a very long time. Also it's not the miners that have to put high transaction fees we do and not them.