Simple calculation - Now population is 7 billion people, in ~2100 world population may be 12 billions. So, then by average, one person may have 0.00175 btc. In reality, it may be smaller amountdue to lost bitcoins. But we don't have forget that not everyone will use bitcoins - we have to exclude kids, poors and etc. So, I think it will be enough bitcoins for everyone. Another question, how people will have to send small amounts of bitcoins, when fee will be much higher than transacted amount.
Use a bit of common sense.
People pay right now 80 000 satoshi for a tx or 2$.
If bitcoin will reach that usage and will evolve (scale) normally people will still pay 2$ but that probably would only be 2 or 4 satoshi.
Even now people are migrating to alts, Bitcoin has a huge difficulty level in mining and requires tons of resources just to set up a mining farm, I can't see any future where even 100 satoshis worth $1 buck, simply because by then running a full node would cost you as if you wanted to build the Eiffel tower, yup that is around millions of dollars, if Bitcoin wants to survive in the long run we should come up with a solution to avoid making the mining operation too much expensive, right now people having doubts and can't decide whether it's worth it if they were to invest on mining rigs, up to where current miners are willing to invest just to stay in the competition?
Proof of those people migrating to alts?
Migrating and doing what?
You have bitcoin because in most cases you can only buy bitcoins then change to alts and then the transfer... and then you have to go back to bitcoins because only 1% of shops and services are dealing with other coins.
Again, it has nothing to do with the difficulty and mining.
Bitcoin can run with a single person running a cpu miner, the number of transactions will be the same.
Please educate yourself before posting stupid things like that.
I don't believe all of 21 million bitcoins will be available in the future. As you stated above, lots of them has been stolen. And some has forgot their keys and they don't reach their bitcoins as well. So I foresee a shortage in long term.
Throw your crystal ball in the garbage and read again what DannyHamilton wrote.
If you still can understand that, then this is no place for you , sorry.