Misleading title, but largely accurate
It would seem reasonable to read from the public statements that Nokia are still talking about using Symbian in FAR MORE devices in 2012 than they are currently doing now, so "Nokia to cull Symbian in 2012" is extremely misleading.
They also seem to be planning to use Maemo in FAR MORE devices than they do now. All of which implies that they expect to use Series 40 far less, but continue to run a multi-platform strategy. Lets see if that turns out to be the case.
Have you any reference to Nokia denying that they'd replace Symbian with Maemo "at the top end". I don't believe they did, just denied they'd be replacing Symbian with Maemo completely and re-affirming their commitment to Symbian.
Since both Symbian & Maemo are both getting total UI re-writes from scratch with Qt, it seems a little early to call relative portfolio/market shares. Plus Maemo is currently a "one device at a time" platform, rather than a true multi-device platform, and there's a lot of work to be done to make the transition.
To say they're making the switch to Qt 5 years too late is probably true but a little on the harsh side. Qt will be shipping in devices next year and powering their native UIs in early 2011. In early 2006 Nokia was still king in smartphones and everyone was praising the N95 - iPhones and Android were nowhere to be seen. It's extremely rare for a market leader to radically change their offering to fend off as-yet unseen competition.
I don't believe Nokia has an inept record in UIs at all - the Series 40 UI was the best in the world for years, and the original S60 design was sound, it just got over-complicated with far too many features added badly over time and trying to make it seemlessly extend to a touch-based UI was always doomed to failure. Services is another matter - I only hope these are just the pains of a company fairly new to the market!
The Series 80 and 90 UIs needed to die because there was too much developer fragmentation - it isn't necessary to build an entirely new UI framework in order to differentiate device UIs. S60 just wasn't flexible enough to be the one-size-fits-all option.
All that said, I generally agree with the theme of the piece. The best article on Symbian/Nokia/Maemo I've seen on the Register for a long time!