The total of the coins was decided on the code of the coin, just like the number of zeros after the point. And that's something you can't change in the future because it was made that way.
We see some changes in the road, but those changes are to make it more secure or more efficient, not to change the basic rules. When people change the basic rules then we have a fork, and a good example of that is bitcoin cash. But at the end, those decisions are taken by a group and not by an individual.
At the same time back when the code was written there were some minor mistakes in it. Apparently the bitcoins will be unusable after 2106 if the mistakes are not corrected.
https://bitcointalksearch.org/topic/m.54958221
Therefore we have to make sure to update it before that. I do think you are aware of the fact that the forks will only work when everyone decides to download it and update it.
Plus I do think there is a limit on Bitcoins for a reason and the long term holders are well aware of the price increase that would come with a fixed limit. I don't honestly think people will need unlimited supply , we can still make the satoshis workable and maybe even invent some more smaller units ?