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.
That's a fair point but the OP says what it is going to happen if the most of the supply will be lost?
Then no one will have any interest in bitcoin due to the limited supply and that there will not be many buy and sell orders. I don't think that it is going to lose value. Also the option of a fork is possible is something like that is inevitable.