Sure certain very low level items are going to be difficult to update outside of the kernel. Let's use video as an example, it's something I'm really familiar w

Sure certain very low level items are going to be difficult to update outside of the kernel. Let's use video as an example, it's something I'm really familiar with. At the Kernel android provides an OEM version of the stagefright lib and the actual video drivers, those would be hard to update outside of the kernel. What the play store can easily update is newer and better API's to those low level lib's. Right now those encoder/decoder API's were new in OS version 4.1 ( I think 4 something, just woke up :) ) but using the google play updates new and better API's could be rolled out at anytime.