Nokia made several mistakes that led it down this destructive road. Nokia stuck with Symbian too long and then hedged its bets with a new OS from Intel and finally selected Microsoft as an OS partner. Nokia had the opportunity to select Google and Android at the same time, but selected Microsoft, because Microsoft offered cash and to do most of the software engineering work. So, Nokia made one bad choice after another.
However, this split will allow the company to focus on other areas and let Microrsoft worry about a dwindling handset unit. Will this really increase Microsoft's chances in the handset market? Probably not, but Microsoft will continue to through money and resources at it. The real sad part is that Nokia has produced some really good hardware, but it's the software choices that have been the downfall.
Looks like Nokia has got a deal here!! Not sure if Nokia re-aligned its strategy to make Windows phone thinking about this possibility of making a deal with Microsoft, but I would tend to think so. Now the question is if Microsoft got a good deal or not...only time will tell. But atleast it could be thought as the last chance for Microsoft to make a desparate turn around in the mobile market.