Unless the person has the Private Key to access to Bitcoin funds, any lost Bitcoins will be lost and untouched forever.

As it is impossible to find the Private Keys which are lost, you may consider that the funds are unavailable in this case.

Bitcoin is a complete digital money, thus you must make sure that you have the information to access on your device.

What will happen to the lost Bitcoins eventually?

For user’s side, the Bitcoin is simply inaccessible and lost forever.

For market’s side, the amount of lost Bitcoin will be removed from circulation. This will lead to higher price of Bitcoin according to “supply & demand” theory.