Well there is a probability for that to happen but i don't think that it will happen right away. You see bitcoin took a lot of years to be in where it is right now. So i think ethereum will take about a couple of year to take over bitcoin.
But bitcoin is not going to remain static either, in this year many people were predicting that ETH was going to surpass bitcoin in market cap and suddenly out of nowhere bitcoin grew a lot and now there is a huge difference between BTC and ETH and the same may happen again if ETH gets close to bitcoin once again.