Because the number of bitcoins is limited, when all bitcoins are mined, all miners will face unemployment
LOL, when were the miners employed anyway that they will become unemployed? Your basic understanding is flawed here, miners dont mine as a job, it is a voluntary thing to do. Anyone can stop mining at any time if they wish to, it will only make the proportionate rewards more for the rest of the miners.
And mining will not stop after the last block is mined, transactions are mined and they will continue, so mining will too.
(may continue to mine other cryptocurrencies),
Once a miner becomes a pro at mining a certain coin, it is very less likely for them to change over, but this might be a personal choice too.
People will not sell bitcoins after only bitcoins, and wait for the value of bitcoins to gradually rise.
It will be 119 years from now. We cannot predict what economy will be present then.
Bitcoin's transaction volume will decline. Many whales will not profit by selling bitcoins to buy bitcoins, and the return of bitcoin's volatility is gradually decreasing.
Why would someone sell bitcoin to buy bitcoin - makes no sense. Unless you are selling for fiat and then using fiat to buy back - then that is a good thing to do. Scarcity of bitcoin is always rising, so the price will also rise - people would want to spend their bitcoin more carefully and likely the price of goods to buy using bitcoin will be low.