Well you posted this in the "Economics" section, so let's make this about economics.
People have an amount of BTC. The higher the value of their BTC, the more likely they are to keep it in safe locations or spread it between different places. So the chance of them losing their BTC decreases exponentially as the price rises.
If they lose BTC, the supply decreases, therefore making the remaining BTC supply (marginally) more valuable and making people less likely to lose it. So it never reaches a point at which there's not enough left.
So basically, no. It's impossible.
As long as storage and transactions are handled by humans, there is no way to avoid human errors, regardless of the assets value. Sure it is less likely to be lost, the higher the value. But will it ever be totally secured just because it is of a certain high value.
I am not convinced.
Bitcoin that is lost because of code misplacement does not disappear from blockchain rather it simply means the individual would not be able to use it again . Therefore, the individual's lose and not that the margin of bitcoin available decreases.
Furthermore, as for not being convinced about "totally secured ". Bitcoin itself is totally secured when you take your time to do the right things to secure it. This brings us to the misplacement of code or disclosure to untrusted third party. So we have to be careful.