[leonatan]

What 8GB devices? Even iPod Touch starts at 16GB and is supported.

[threeseed]

iPhone 4S and iPhone 5C in 8GB configuraitons are still being sold around the world. They are both capable of iOS8.

http://store.apple.com/us/buy-iphone/iphone5c/iphone-5c-8gb-...

And by disk space I mean after the user has installed the typical number of apps, photos, music etc. My partner is an example of this. She has to choose between deleting apps and doing OS updates.