You guys are looking at this all wrong. Google will not shoot themselves in the foot. The IP Portfolio is worth more then what Moto Mobility profits per year. Yes, I'm sure Moto devices will start shipping with updated versions of Android, and I do see big changes for Moto as a separate company, but they are hardly the biggest device manufacture for android (not globally anyways). Google wants everyone in the world to have their search engine, Android is just another way to make that happen. The more Google services people use, the more money they generate.
Here are some fun facts for you:
Google made $30Billion last year.
MotoMobility made $12Billion.
Now this was not profit, just pure gross, but I promise you, Google turned a much higher profit
Don't worry about it, Google is not in this for the money, they want the patents, and they want to save the sinking ship (yes, moto is sinking) that launched Android to the masses.