With Bitcoin having the largest market cap what could Ethereum possibly do to overthrow Bitcoin from the number 1 position?
I'm sorry to burst your bubble mate but Ethereum would reach bitcoin in the future. Why?
1. ETH is also not immune to scaling issue as bitcoin.
2. ETH current supply is over 90 millions. Bitcoin is capped at 21 million. So bitcoin price will go up because of the limited supply while its gonna be hard for ETH to increase its price because the supply is growing.
3. Bitcoin has a backing of a nation - Japan. ETH has none.
There's a lot of factors that inhibit ETH to really overthrow bitcoin. But I wouldn't worry about it. Because ETH will be the dominant altcoin and ETH smart contract will be its selling point.
However, if you are curious or just want to watch if this could happened. Watch it here:
http://www.flippening.watch/Its the website ETH proponent put up in June when ETH was chasing bitcoin in terms of markecap and trading volume. But this so called flippening didn't happened. But is fun to watch it though.