Google was just reported to have issued a memo to OEMs detailing what versions of Android must run on certified devices. Though it might appear as a rather strong-arm tactic, it might just be the forceful push that the platform needs to finally dispel the thorny issue of fragmentation.
The leaked memo basically says that OEMs interested in getting access to Google Mobile Services (GMS), the collective term for Google's apps and Google Play access, on their upcoming devices must make sure to have the latest Android version running on them. Or at least nothing older than two releases back. In practice, this means that new smartphones and tablets should be running Android 4.4 or, at the very least, Android 4.2. This new policy is set to take effect starting this month.
The leaked memo matches another previously leaked document listing the GMS approval window for each Android version. It basically says that no new devices running Android 4.1 or earlier will be certified. Google is giving OEMs at least 9 months after a new Android version is launched to have their new devices certified, which could cause no small amount of headache for manufacturers who have their own development schedules.
This might sound like Google trying to exert a stranglehold on Android once more, but the situation of platform fragmentation could very well justify it. Users will certainly benefit from having the most recent or relatively recent Android versions on their brand new devices. The burden on device manufacturers, however, is now heavier and the impact on smaller companies might be considerable. That said, the policy really only applies to devices that want to ship with GMS, and some don't. It also only dictates the window for certification but leaves the schedule of announcement and launch still up to manufacturers.