Actually this is exactly what I see happening on a very limited scope though. With Apple's discontinuation of their Xserve line, I believe Apple is preparing to allow a few 3rd party licensees to sell enterprise class solutions (hardware and software) based off Mac OS X Server, while Apple concentrates on the home server market. The back-end, workflow market isn't very profitable in terms of hardware anymore and never was glamorous enough for Apple. Plus the overhead of supporting IT was something Apple has never been good at. Another company, such as Dell or HP already have the support system setup for IT, I'm sure they would love the opportunity to add yet another solution that they can push to clients as iPhones and iPads infiltrate IT departments.
At some point Apple is going to want to slip into the IT back room, if only to add seamless support for their iDevices, Macs and iCloud.
Just to be clear -- my preference would be for apple to do this themselves, but if they don't want to dilute their focus for a smaller market like this, then I hope that they do license OSX so that this market can be served. They don't have to license OSX broadly, just to one or two "anointed" OEMs. And they should charge enough for the license that it's not economical for anyone to compete with them in the home market (maybe charge $200 per seat or something).
If Apple refuses to license, then perhaps someone like Rubenstein could start a company that builds an OS off of Darwin. For a server or high-end workstation target audience, it's not critical to have exactly the same UI as OSX. Just a thought...