There’s some interesting new research by CIRP (pdf) that shows people are more likely to switch from iOS to Android (20% of users) than Android to iOS (16%). The net flow is in a different direction than the media (or Apple?) had us expect and the actual percentages are higher than I had expected. The CIRP report says that changes in OS happen more often when users change carriers. It seems people are not so loyal about their mobile OS after all.
Device upgraders and OS switchers bring extra challenges for developers. For some apps, you might want to consider how users might migrate data to their new devices. This might go beyond normal OS app backup schemes if you also wish to also support OS switchers. You might also like to think about in-app purchased items but in most cases if the user changes OS they won’t expect to keep purchased. Exceptions are usually subscriptions, like Spotify or Evernote, where the user will expect to continue with their subscription.