I agree that Apple has migrated to new technologies and lacks the configurability, but what I meant by stating that I did not believe that Server was shrinking was that Apple is merely changing the target market. I apologize that I did not make that more clear. Back in the days of OS X 10.4-10.6, Server was a fully enterprise class server operating system. With 10.7, Apple made it a layer to be added upon OS X, rather than an independent operating system.
Quite honestly though, I don't think that anyone can blame them. Aside from certain corporations and universities, OS X Server was rarely deployed. Microsoft and in some instances UNIX servers were the go to platform. Since Microsoft essentially set the standards, no one would consider Apple. Furthermore, OS X Server's cost due to the fact that it was an entirely different OS put it out of reach to the average guy looking for a good home server, small businesses, and smaller educational institutions. While some view OS X Server as dying, I see it simply as rebirthing an old product to a new market. The market that Apple goes for with Server 10.7 and up is one that Microsoft hardly plays in, and Linux is not as widely used.
Think about it this way, Microsoft sells various editions of Windows Server for various target markets. Some versions lack the functionality that even OS X Server offers, and others have user account limits and other forms of nonsense. Apple tried the corporate full functionality that Microsoft offered, but they made barely a dent into the market and made very little money off of it as it was out of reach to many. Let Microsoft handle the high powered servers that power our government, universities, and corporations; let Apple handle the home users, the schools, and the smaller businesses. I know $20 is a very safe price for the features offered, and I don't see Microsoft offering anything in that category.