It's worth remembering that Microsoft's action came just 2 days after Tom Tom announced that if things got worse then they would be in violation of loan covenants. Yet the patent wasn't new. What was new was the temporary weakness of Tom Tom.
If the US system of 'patent everything' and endless lawsuits from trolls is working, then why is their economy in free fall?
They tried to build an economy in which they can buy and sell the RIGHT to make something, but ended up just killing their own industry with endless troll lawsuits. Now, even the fact they have the worlds reserve currency and can print money, it cannot save them.
You cannot export a lawsuit, you cannot package lawsuits into bonds, and sell those bonds on. You cannot make an economy of lawsuits and IP lawyers. Why do you think only a tiny fraction of new technology is ever launched now in the US?
You CAN build an economy making things and exporting them, but you CANNOT build an economy on PREVENTING people making things and NOT exporting them.
Microsoft is toast and they know it.