Bitcoin is 89% premine to any kid born today.
In 2140 it is 100% premine to any kid born that year.
2140? Ah, sadly, I was unthinkable for years that had not necessarily arrived. Well this is why it is difficult for us to grow day by day, because we make too many plans far enough as you say 2140. why not designing a strategy for today and for tomorrow is much better, than you have to plan the rewards for the year. do your best for now and get started.
And one more thing, for every generation there will always be reformers, and even new Satoshi will be born according to their time, so don't worry about future generations getting rewarded or not. rest assured they will be much more developed than we have today.