Well thats a question to be handled over the next generations as i doubt we will be alive by 2140 thats when the mine of bitcoin should be over,but sure there is a concern since no more coins,what the miners will get to keep bitcoin security,or what will happen if the hash stop protects bitcoin what would be the next step?
I still hold hope for some kind of technology that will allow us to still be here. I would think it would be a whole new world at that point and bitcoin should finally be the currency of choice, fees would they be enough for miners to keep on mining? who knows, would be nice to have a time machine to have a quick look.