Personally I’d like to see an ad-supported, or partially ad-supported version that isn’t evil.
The way Google started out with relevant ads in the sidebar or a single relevant ad at the top is acceptable in my opinion if it means bring the cost way down for the end user and ensuring sustainability for the company.
I don’t think asking users to shell out $10, $20, $30 per month for search is a viable long term model that’ll ever appeal to the masses.