Apple needs to get the rest of OS X onto the server. They could build their own servers again (unlikely), or at least license OS X Server to Dell/HP/IBM/VMWare/etc..
OS X Server is really a shell of the former product. It used to be a great small business / design studio server, but it has lost most of its use-case and I really question its use outside of a few Apple Device Management scenarios.
Almost all the documentation and best case expects Macs to be tied to an Active Directory / MS environment for management.
As a typical Web / LAMP host, OS X really is not that performant. Unix tools execute faster on a RHEL/CentOS box then an OS X (even if the OS X box has higher specs). MySQL is particularly bad if it hasn't been tuned, and most of the literature seems to indicate that OS X (or more specifically MACH) doesn't have the level of optimisation for server workloads.
That being said, if your using the OS X frameworks, there can be some great value with exceptional performance (just look at the startup using Mac Pros as image manipulation servers).
I think Apple who did do servers at one time have found the consumer side of things more profitable. That said, they by not doing servers are seemed less hostile in server providing vender partnerships and this I believe would be more profitable for Apple than going into servers.
Now with the move of things into just the app bare bones style docker VM's in which the app is a service upon a server then maybe some form of runtime that enables some applications would be useful, maybe.
But if they went into the server market, then the trust of doing partnerships with server focused vendors would diminish. Though VMWare would probably be just as happy, if not more and that would be about it. IBM, for the arrangements they have now, work for both of them too well to upset I feel.
Back when they did servers they did it for two things, render farms and studio networking.
Render farms have largely been supplanted by Linux, and studio networking can either be handled by a Mini on the shelf or a Windows server in the closet.
Very true and probably more so when Job was somewhat into computer render animation. That and attention to a good working audio driver setup and API's have helped keep Apple still in the audio DAW industry. AS you say much has changed and can see why they shifted focus. Though I do as many wish they at least had a server flavour, more so given would not be much to change I feel as to what is already there. But exposure to a consumer messing up and a sever messing up can be vastly different in support/costs to make sure 100% right and less customers.
Still they do like consumerising things and who knows, personal home iCloud that sits in your home would perhaps be a likely server offering if any they may take as targeting consumers. That if any route is maybe the one that could happen.
I really wish that the airport extreme routers would expose an itunes home sharing service, so that those of us with laptops and way too much music/videos could stream to airport express/appletv/itunes home sharing without having to have a machine dedicated to the task.
I knwo you can add discs via the USB port and with hub can have a fair few and can network share and backup to them. But not apple user fully and did look but found nothing to enable sync with iCloud beyond a desktop option, though may of missed something. Though did find this: https://support.apple.com/en-us/HT204618 which pertains to remote desktop and related functionality done via your iCloud account, so maybe, though still need to access via iCloud, which if just athorisation would be ok if you had a fallback option.
