But I hope that delta updates are still not being implemented - I really don't expect Apple to make an update that doesn't require a factory reset on their base

But I hope that delta updates are still not being implemented - I really don't expect Apple to make an update that doesn't require a factory reset on their base devices before update. That would be very futuristic. Just like reliably fetching my emails - though it was stable like a concrete block in iOS8, I understand that times change.