Tons of reasons for BTC to be market leader and it is because BTC is a secure, decentralized, immutable, transparent, transnational, open, censorship resistant robust payment system. Scaling is an issue that will always be present therefore it isn't a true issue. I don't think any of the concerns you listed are true concerns for Bitcoin and the points you made for Ethereum they seem weak as to why ETH would usurp Bitcoin. I don't see it happening but then again I only see Ethereum as a tool to make ICOs. It provides nothing beyond that as of now.