There is a possibilty that one day there is an altcoin that will challenge bitcoin , but that will happen in the near future. For now there is no altcoin that could break what bitcoin has today. There are many altcoins in the exchange markets that have been pumping in their designated value but none of them reaches the half of bitcoins value. Bitcoin will always be the king of all digital currency,
Definitely that is something that can not be completely discarded,almost everything is possible and that is one of them,just look at the large number of altcoins that appear very frequently,in one of those and it can happen that it's just as disruptive as BTC is,but I do not think it happened too soon,those things take some time and it's not something that happens overnight,for example,some of those that now exist seem very advanced in terms of what these intend and their development.