Let's suppose that for some reason the supply of potato drastically decreases all around the world. Does that mean that people will pay 10.000 dollars for a potato or give up their cars just to get a potato? Of course not. This is because the utility of consuming a potato - the want-satisfying power of a potato is much smaller than that of a car or of 10.000 dollars worth of goods or services. In other words, from the mere fact that the supply of something is limited it does not follow that the price will soar.
In comparison to a potato, Bitcoin is not even a physical tangible good that can be used for satisfying human wants or needs, and its only utility is that it functions as a medium of exchange. So, just because Bitcoin supply is limited, that does not mean its price will rise. People will NOT pay enormous amounts of money just to have a medium of exchange function, especially if this function is equally available whether the price of Bitcoin is 1 cent or 7.000 dollars, and if this function can be realized with various alternative cryptos or fiat money.
Supply depletion is not the main cause of price inflation, demand influences it also. If the supply keeps reduced and the demands are low it won’t create inflation. Then the usage dependence, in this case Bitcoin, won’t be as simple as changing it to altcoin even to anything else. The huge amount of altcoins could break the market so there will be no market centralization could make transactions difficult.