Sigh....MSFT didn't have to do a damned thing, neither did Elop as Nokia was already fucked as they pulled the same shit that Palm did, wasting their time at #1 pocketing cash and going in a dozen directions at once instead of actually innovating and staying ahead of the curve!
Break down their sales when they were last #1....what was that? It was nearly 100% Symbian "feature phones" with an OS so damned old it felt like running Windows 2 in 2005? Bingo, we have a winnar! Symbian was waaaaaaay too fucking old to compete, hell I saw that all the way back and Android Donut (1.6 IIRC) which made Symbian look like the fossil that it was. What about Maemo you say? What about it? If you go look at the actual reports coming from the devs working on the thing you'll see that Maemo would take at least another year and a half because they were having serious memory leaking and file corruption issues. Remember this was when Android 1.5/1.6 and iOS 2 was out, no way in hell would the consumer have taken a phone you had to reboot 4 times a day, could crash when you took a call, and turn your files into data salad, not when they had choices that worked!
Look I get why Nokia fanboys wanted to think some "bad guy" just killed poor wittle Nokia, I had a Nokia for ages and AAMOF I just picked up a Lumia for the wife as she didn't care for Android and while I hate Metro with a fiery passion I'll give credit where credit is due for those not "tech heads" its pretty damned intuitive and the hardware as always seems solid but....the one that killed Nokia...was fucking Nokia. It really was Palm all over again, when Elop came on board they had not ONE OS, not TWO OSes, but fucking THREE OPERATING SYSTEMS splitting up the talent and sucking down resources. They had 1.-Symbian, 2.- Maemo, 3.- the dumbphone OS, and wasn't there even a fourth one for awhile? I seem to remember they were also working on a Java based one there for like a year and a half.
When your only selling product, top of the heap at that moment it may be, is the equivalent of VHS when the entire industry and an ever growing segment of the populace was buying DVD? Well that is when your ass better be laser focused on beating the other guy to the punch, instead they split their resources all over the place and by the time Elop showed up? It really was a "burning platform" as Symbian was too fucking old to compete, dumbphones were going the way of the 8-track, and Maemo probably wouldn't have gone gold until after Apple 3 and Android Gingerbread had been out a good 6 months and by then they were royally fucked.
In a perfect world they would have bought WebOS but they couldn't compete with HP throwing stupid money and Android was in a race to the bottom so Elop bought the only other OS available,and it didn't work out, it was a Hail Mary but at that point a Hail Mary was all that was left, the other guys simply were too far ahead in the game.