You know what? I think this question was happening when the first time bitcoin introduce, and I think many people underestimate bitcoin and they don't think that bitcoin can get the highest price. But after bitcoin start the journey, you can see that people interested in bitcoin and they willing to buy bitcoin especially when bitcoin is less than $10 and they keep the bitcoin for a long time. And suddenly, in 2017 ago, bitcoin price was exploded, and many people who have bitcoin was making a lot of money.
We believe that bitcoin can increase even more than $20k, but still, no one will know when it's happening. And I guess this is why people keep buying bitcoin right now because they don't want to miss this chance. I think some people still trying to deposit their money and buying more and more bitcoin.
And the mining part, when the difficulty increase, I am sure that the mining hardware company will start to search another new technology that can support the mining so the mining process will continue until the last bitcoin. When the first bitcoin was mine, we can use the old computer to mining bitcoin, but soon, after the difficulty increase, we need to build new hardware that can handle this. And you can search on eBay, Amazon or another store online and you will find Antminer, Scrypt-miner hardware that used for mining.
I am sure that soon, there will be new hardware that can support the mining process and I heard that Bitmain would (or they already) launched the new Antminer hardware. You can visit on their site to know more about this.