Yes. But a fork might change that. As a current example, the Segwit2x fork that has been announced for 28 December proposes to redistribute Satoshi Nakamoto’s coins.

What do you mean redistribute? Is this new fork segwit2x will distribute a new coin to a current active bitcoin wallet adress? Is the old wallet adress that not active will not recieve a new fork segwet2x coins?

This question is asked many times before.Why not just search around the forum,instead of posting new threads.If the bitcoins are stored in a cold storage-hardware wallet ,somebody could find it and conduct a brute force attack with some software and crack the password.If the bitcoins are on an online wallet,the company that runs the online wallet service could deactivate his account due to inactivity and get the bitcoins.

Bitcoin remains 21million in Blockchain but because the owner of 1million Bitcoin dies and nobody can access the wallet so only 20million Bitcoins can be used accessed
Only Bitcoin owned by Satoshi will be redistributed or all old inactive Bitcoin addresses?

it is very unfortunately if happened.sebenarnya there is a solution to prevent it happens the solution is the same as the inheritance.If you have a bitcoin in large quantities then you think it must be inherited in your child.soon and tell your account and password bitcoin on your child so that your child can continue your bitcoin business and will not just disappear.

its similar to ancient history, lost treasures of gold in the ocean and under earth. people forget the location or their ship sinks. probably we will see something like this in the future: (bitcoin treasure hunts) 

a solution would be to make it that wallets that are inactive for ~20+ years become re-minable

it has a possibility that it may lost or just stay it depends on the situation how about if he had get to know on it how about if he tell it one of his family and teach them on how they are able to manage this. for my opinion this scenario will always depends on the situation that are been given for.

yes in fact we have less than 21 million because bitcoin was less than 100$ and many lost wallets with many bitcoins "i know some one lost wallet with 500 bitcoin" all this make 21 M is ideal number.

Yes, if someone dies, or even if someone loses their private keys to their wallet - the bitcoins in that particular wallet are lost forever (basically). In the future we will probably see more and more people inherit bitcoins, so that they aren't lost. If someone with 1 million bitcoins dies and the private keys are unknown - then yes, those bitcoin are pretty much stuck where they are.

It's unfortunate, but people have suggested for inactive bitcoin to be able to be re-mined and other such ways to make sure amounts of bitcoin aren't lost forever. There are of course issues with this to do with security and otherwise so we will probably see the status quo for this scenario to stay the same for a while.

This is why we also need to atleast note the guide how to take our bitcoin for our family member, teach them how to used it
Give them our legacy that we invested.

So our works, will not become nothing