It's not impossible, but it won't happen. Maybe there will even be a new coin or another coin that will surpass the BTC, but this coin is certainly not ETH. The economy, a structure that has already developed around the BTC, is enormous and this won't be affected so easily. There are many factors that inhibit current prices, but in 10 years if you have to bet on who will survive and still be number 1, betting on ETH is really being very brave.
Nothing is impossible of course, but realistically speaking it will be hard to surpass Bitcoin anyway. It could happen though because there is some intrinsic incentive to it. If Ethereum gets closer, there could develop something similar to self-fulfilling prophecy. The closer Ethereum gets, the more the people are excited to see Ethereum surpass Bitcoin.
I agree,its really hard for Ethereum to surpass Bitcoin. For all the new users that get to know crypto all of them first use Bitcoin and once they start learning more about crypto they start to consider Ethereum first. But mostly everyone starts with Bitcoin and they only heard about bitcoin. 95% of people heard about bitcoin and the other 5% know about Bitcoin and Ethereum. Bitcoin is the most known cryptocurrency in the world and will probobly stay like that for 10-20 years.