It won't occur if the cost of bitcoin nevertheless at the high price. Since bitcoin that have really large price for every coin. To exchange bitcoin, that crytocurrency need to be more good and also have a new 'thing'
As of this days, bitcoin is very demand and popular in the world of crypto currency. Its value, is getting high and it will never be replaced easily, maybe there will other crypto currency someday that may compete bitcoin but it will never replaced easily the performance of bitcoin.
Bitcoin is very strong and it's hard to replace bitcoin basing on what is happening now, when it pump altcoins will bleed and we know only one of the altcoins that we are seeing now can replace bitcoin, probably Ethereum but it continue to go dump as bitcoin is moving the opposite direction.
Well it's possible that bitcoin can be replaced by another currency but these current alts don't give us much of a choice, maybe there are others in line with better technologies behind tyhat that might completely outdo bitcoin but until then i don't think any of the current altcoins can overtake bitcoin.