In my vision, these companies (Samsung, HTC, LG, etc) did not "invested" in Android. They used free Google software to actually save their own skins. What chance any of them would have in the smartphone transition using their own home-made software? I dont think they have much options now, the Windows Phone choice is not giving good results for Nokia and I think the only choice they have to compete against Apple is to have an unified environment so the users can benefit of more apps, and this is exactly what Android gives to them, for free.
"the Windows Phone choice is not giving good results for Nokia"
Nokia's problems have nothing to do with Windows Phone. They're still offering lots of Symbian handsets [http://www.nokia.com/us-en/products/products/] to compete head to head with iOS, Android, and WP7. A renaissance for the brick format or Symbian was no more likely a year ago than it is today.
For me, it's hard to see how betting on a MeeGo app ecosystem would have given them a growing market share over the long term.
Android rose because it was cheap and available as an alternative to iOS. Google realized a first mover advantage in the "not Apple" segment of the market. Now with Motorola Mobility purchase, they have the opportunity to bring more of the profits back in house.
I suspect that Google's long term hardware strategy, if they have one, is to go head to head with Nokia in the developing world by deploying the next generation of feature phones and collecting data in rapidly developing markets like Africa.
If Android, then Nokia would be in the same boat as HTC, Samsung, etc. are today...paying Microsoft to use Android and facing the prospect of going head to head with Google's house brand.
Note how Motorola and Sony do not pay Microsoft for using Android.
All the other Android vendors license Windows for some other area of their business. These two do not and Microsoft has no leverage to force them. (Yes, I know about Microsoft suing Motorola and Motorola suing Microsoft back).
