Nokia has been aggressively working towards a very clearly defined strategy. Sure, they've been slow to implement it -- too slow -- but it's nearing completion and ready to bear fruit. The Symbian rewrite is a two phase strategy that will ultimately help Nokia in its bid to democratize smarpthones. You can already see how Nokia is shoving what were once high-end smartphone features into incredibly cheap handsets. The first phase will hit devices in weeks as Symbian^3 and is a play to make existing Symbian users (of which there are millions) feel like their OS and services are modern. Symbian^4, due sometime in 2011, then takes the user experience to the next level. Remember, we're still only talking about Nokia's mid-range devices. There's also S40 at the low end.
MeeGo is Nokia's high-end strategy. The open-source project it began with Intel back in February to unify their Maemo and Moblin software platforms. The first handset is still officially on track for this year (though that could slip) and already looks very much like a flagship device if that N9 leak is valid.
The link between the two mobile operating systems is Qt, Nokia's software framework. The idea here is that if you write an app for Qt once it'll work on either OS. Nokia's spent a lot of time and money to bring the software to the level it is today. And based on the feedback we're hearing from developers, Qt is living up to its bold claims.
So, we already know Nokia's thoughts on Android. The company has made it abundantly clear that it won't pee in its pants for short-term financial warmth. That brings us to Windows Phone 7. Granted, Elop is coming from Microsoft so it's natural to assume his role as Nokia CEO could ease the way for even deeper collaboration between the two companies. But think about it, Windows Phone 7 is a complete re-write of Microsoft's mobile phone OS... just like MeeGo. There's absolutely no advantage to Nokia ditching MeeGo / Symbian for an unproven mobile operating system today, not with Nokia's vast base of existing users. And what would Nokia gain by carrying a fourth OS, essentially throwing itself into the cut-throat role of another Microsoft OEM when Nokia's profit margins are already razor thin? Nokia is hungry for those big juicy margins enjoyed by Apple and RIM, companies that differentiate themselves by owning the hardware, software, and services they sell.
Of course, if MeeGo fails to catch on (a very real possibility) and Symbian^4 and S^5 for whatever reason can't step in to fill the void then all bets are off. But until then, and we're talking a few years out, Nokia isn't going to replace its operating systems with Windows Phone 7 or Android, so stop it.