Bitcoin will always have its place in the cryptoworld but its dominance is going to be replaced soon. Ethereum is currently the top contender but if not that then next year something else will probably rise up.
I haven't been here long, but from my research, I don't see bitcoin being replaced because of how long it took to get to this point. There might be other alt coins that reach the same price. And maybe in time they will have as many transaction as bitcoin. But bitcoin is the oldest and I think people will always respect that.
It is the mst poular and used digital currency of the world, if you say digital currency, one word will come up in your mind, Bitcoin. Ethereum has a good future before it, it will be the first altcoin that will follow the footstep of bitcoin to it's fame and price. But it will never replace bitcoin, never even a lot of years will pass. Bitcoin will stay bitcoin.