The problems they are likely trying to solve are business and legal, not technical. Pesky things like not having to release keys bits of code under a 'free' license (i.e. they have no choice but to release any changes to the Linux kernel under GPL as that's what it requires.) Sure, they'll probably still release large chunks of source code (possibly under MIT/BSD, possibly under a less liberal license) but keep strategic bits closed source. Right now they have to do this via the clunky and somewhat obvious Google Play services layer. And then there's the constant potential exposure to lawsuits. etc.

By being able to decide on what pieces would be released under what licenses, it would allow them to prevent competitors from following in their footsteps as Amazon and various Chinese companies have done with Android. Things like this are the reason Samsung (one of Google's largest problems) keep pushing forward with their Tizen platform so that when the shift comes they have the ability to sidestep it if they want to.