Bitcoin will not become extinct or reach a value of zero just because all coins have been mined and even then it is predicted that all the bitcoins will only be mind by 2100 something more than 80 years from now, so much could change then cryptos and the markets are still evolving day to day so who knows in 80 years what the situation could be like!
The market is constantly changing and no one knows ahead of time but I believe that bitcoin and its existence along with this market are developing very well due to the bitcoin scarcity in the next few years. Investing in bitcoin is the best choice I have ever made.