I think this case can be happen in the future when the total supply amount of Bitcoin is mined out then the price of Bitcoin will dump then there are some better altcoins will replace Bitcoin in cryptocurrency market like ETH or XMR. But as I know total supply amount of Bitcoin will be mined in at least next 100 years so I think we still no need to worry about it in at least next 50 years 
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I figure this case can be occur later on when the aggregate supply measure of Bitcoin is mined out then the cost of Bitcoin will dump at that point there are some better altcoins will supplant Bitcoin in digital currency advertise like ETH or XMR. Be that as it may, as I probably am aware aggregate supply measure of Bitcoin will be mined in at any rate next 100 years so I think we still no compelling reason to stress over it in at any rate next 50 years)