ethereum has so many advantages comparing with bitccoin. it is faster, has a larger network size and fees are less. so i think ethereum has a potential to reach the top in long term. and vitalik is a such a clever guy that can make it happen.
Althoguh the whole market is just not dependant on the coin features and frankly speaking it doesnt do much but its community to judge which coin deserve to have certain amount of value.
Being better than bitcoin in technical aspect doesnt instantly mean it will become #1
Reaching top can't happen instantly for ethereum. This is like a progress and it will take too much time. The adoption level will go up first worldwide and then something will happen accordinly.