"Fragmentation" was an issue with older (Android 2.x) devices, but for 4.x and forward, has been fixed. Any high-end Android phone made in the past 6 months and going forward runs 4.x and will easily upgrade without issue down the line. Does this mean that every Android update will immediately propagate? No. But remember, iOS updates don't come out every couple of months either. Sometimes you need to wait a full year. Will current phones *indefinitely* be upgradable? No, but same with iOS as well. An Android 4.0 phone will handle 4.1 and 4.2 seamlessly, extending full usefulness for a couple of years with nothing breaking or being lost. Might 4.3 and beyond cause some features to be missing? Sure. Just as iOS 6 placed on an iPhone 4 (the latest iPhone just 1 year ago) will lack Siri, YouTube, and good maps. For these reasons, most iOS users are choosing to pass on the latest upgrade, even though their older iPhone can run it.