Pipe dream, perhaps. I don't think it's likely move from Redmond, that is for sure. Totally practical or a guaranteed success? I would not suggest that.

That said, a big move is in order. Not a product, not a new CEO, but a new mindset being delivered to the public.

Open sourcing a core product is a solid post-Ballmer, industry-mind-blowing sort of move that they totally need to rekindle the developer base for the mobile/cloud/wearable/etsy/kickstarter era. Acknowledge and embrace commoditization -- it is a modern "aikido" style strategy move. Use momentum to gain momentum and throw the opponent.

Fighting the inevitable is just ugly and once you lose face (confidence of developers aka R.I.M.) the downhill slide is just that much uglier. Keep in mind they have made some grievous PR moves by missing Tablets and mobile phone market (so far!) For example, Ballmer said iPhone was not going to gain marketshare:
http://allthingsd.com/20130824/beyond-monkey-boy-its-a-steve...

So it's maybe(?) time for some humility and "going back to the base" which in Microsoft's case probably means their developers.

Think about it... Microsoft spent unbelievable sums developing their army of Microsoft developers -- VARs, consultants, and IT developers who were all sold on the Microsoft stack because all of these software products are marketed and sold to be used as a developer platform and as a gateway to riches selling 3rd party apps to Windows users.

I think we all know where this story is heading. Many dedicated Windows devs are now eyeing Apple's appstore with envy or retooling their skills to use Google AppEngine or Linux on AWS or whatnot -- just because that is where the money is and it seems as if mobile is the end-user platform of the near future, and MSFT is not getting there with Mobile Windows yet.

They're not even exciting us by putting out a WinWatch or a WinGoggles to walk around with in some future utopian vision. Only now 5 years after iPhone do we see a great tablet and phone operating system from them.

So they don't own the high ground with developers they once held as the "one and only platform king" and they don't own our vision of the future as well.

In this way, specifically, I think this is how Windows is different -- if it went FOSS, this army of developers would instantly become twice as empowered. It's a real once-in-a-lifetime opportunity to take control of a situation that is heading somewhat downhill, before it becomes a desperation move, thus actually attracting said intelligent, self-interested open source developers.

Platforms do benefit from Market Share growth due to the network effect, and vendor lockin of building apps on a platform (cost of switching is really high...) and the fact is that once market share is achieved that MSFT and the 3rd party devs (see above) can sell even more of the proprietary stuff that only runs on Windows (a shrinking number at this point...)

When it matters, to replace Windows license revenue, simply "give away razors, sell blades" by replacing Windows license (contract) revenue with support (contract) revenue.

The support is provided anyway, of course you don't tell Fortune 500 CTO to pound sand if there's a bug.

So just change the game a bit. Make the same (or more) money. Go from being hated (UGH another windows upgrade) to loved (WHOO MSFT Open Sourced Windows! frees up budget for new Windows application development let's buy some SQL Server!)

And in practical terms, here's what the invoice lineitem looks like:

SKU-100 | $99/year | Enterprise-wide Guaranteed Bug Response 1 hour Turnaround / per user / annual subscription - Open Windows 2015

The open sourcing process will be somewhat expensive but can be done in tandem with Windows 9 release and really stir up some action on the Operating System front.

They cannot rest on laurels, Google will sooner or later get that magic Chrome OS up to snuff and it's open source people and if it gets market share they will clean up on services.

Google: Giving away (ChromeOS) selling (Google Online Services). It's not that revolutionary of an idea.

In the end, revenue and profits of Windows is maintained through support subscription and Enterprise add-ons.

There could be a lot of new revenue models that seriously benefit from a FOSS Windows like developer training fees and AppStore royalties, but the entire Windows developer world including Mobile becomes open and fresh, new and promising, and with less risk, more security, and a brighter mobile future.

It's just an idea... worth considering.