According to PadGadget, just a few days after its release the iOS 5 was installed on 1 in 3 devices capable of running it.
When starting to develop a new app today in XCode I have to choose whether I want to use StoryBoards in it or not. If I choose yes, I will not be able to compile the app so it could run on the devices with the lower iOS versions than iOS 5.
In order not to leave more than two thirds of the potential users "overboard" the logical step would be to opt out the StoryBoards usage when starting a new app development.
On the other hand when the app is finished (let's say in 1-6 months) maybe 90% of iOS devices will be running iOS 5, thus it would make sense to start the development of a project today aiming for the support of iOS 5 or greater.
What are your opinions on this issue and how can one predict the approximate future usage of a new iOS?