You havnt heard that Blizzard is integrating other old games into the launcher? You know - the games that has a one time fee and zero potential for profit? Same with them having devs working and releasing content for Diablo 2 many, many years after its prime?
Do realize that Blizzard does not have to make cash directly out of every project they do - maintaining their reputation is very important for Blizzards future.
With Classic servers they would easily be able to earn a profit - while keeping their community of diehard fans happy. And I am pretty sure that it is only a matter of time before they actually do it - even their new post is showing a clear change of direction from the "NO" - the a "we want to, but its not that easy".