When will the iphone 4s be obsolete?

When will the iphone 4s be obsolete?

The day it was released

There is still a while before that happens, the most recent obsolete iPhone is the 3, because it does not have 3G. The 3GS is not obsolete yet, so it still probably has another 2-3 years.

It will be at least three-four years if history is anything to go by.

At least 2 more years. Technology has been advancing at an alarming rate though so not sure how much longer after that. Even if you get updates you wont get all the full features.

When Apple no longer makes it, no longer updates it & when iOS apps require a higher version than it can run.

The 1st & 2nd gen iPhones are in that category
iPhone - not made since 2008, no updates since 3.1.3, apps require iOS 4.3
iPhone 3G - not made since 2009, no updates since 4.2.1, apps require iOS 4.3