Most people here allow that (ETH>BTC by market cap) as a possibility, but "long time in the future". My question would be then what is "long" time in crypto world? In my experience crypto currencies are so volatile, that something like Segwit2 will happen (like last fall when many bitcoiners moved to BCH), and ETH can surpass BTC in a matter of a week or two (it almost did at that point). And then drop. But overall my feeling from the answers here is that most people think it's a high possibility due to ETH gaining popularity faster then BTC.