yes it may happen but i think bitcoin has reached to a level where it is difficult for any other cryptocurrency to replace it or reached to its level because it takes a huge time to evolve and bitcoin takes almost 10 year to reached this level. in other words we can say that it is the mother of all cryptocurrency.......
You are right bitcoin has take a longer period to reach to that level and there are a lot of supporters of bitcoin and bitcoin is used everywhere for different services all over the internet so if someone will think that another crypto currency will come to replace bitcoin then they will at mistake.