I respect your knowledge and i have never try to send an ETH to a BTC address before so i dont have a clue but are you sure with what you said because the OP is not the first person to say he mistakenly send ETH to BTC address.
@OP, I will advice to you to be more careful next time cause coinbase dont help with such issues.
Don't have to. I can be wrong too, but it'll be good if it's refuted with some actual evidence instead of just asking if I'm sure.
The format for Ethereum address is completely different from BTC addresses. Even if the software was incredibly bugged, the actual transaction that gets signed would never get confirmed since it's not valid in the first place. These scenarios are more common for Bitcoin forks and/or altcoins that uses similar format but even that is recoverable.
Besides, plenty of people have said it won't be lost. So... yeah, perhaps people should read the entire thread before posting.