They should have known it's a very long term investment. Why were they surprised that it takes time to build up the network? I'm more upset about their reaction, than about the fact that they didn't plan it better. They can make it all successful, but it's long term. Looks like they are affected by short term investors more now.
They are bound to be replaced. They have nothing but ad revenue.
The alternative here isn't that they would run something of that size indefinitely, knowing that it will lose them money. It's Google behaving like every single other company currently in existence: deciding up front that it's too risky and not even trying.
At least it created some nice data showing how the legacy ISPs react to competition. Just in case anyone ever needs to prove that this market isn't working.