It is very interesting to try to grok what might happen in the far future if Bitcoin has taken significant stake in economies. We can scale all the way down to 1 Bitcoin so 100% loss is certainly not likely in our, or our great grand childrens, lifetime.
To clarify:
Even if a whopping 10% of all available bitcoin were lost every single year it would take more than 175 years (from genesis) to reduce the total supply to 1 BTC. This is about as far from "problem" as it's possible to be.