When the update became available for me, it popped up on my phone and I was able to agree/download it or reject the update. I wanted to update mine so I went with it even though it had the option on my network to decline (although like the OP it probably would've kept coming up).
On the other hand, my boyfriend has the same exact phone, and is on sprint, and apparently when his update became available it did not let him reject or postpone the update. Maybe it depends on carriers? I know with mine (on Verizon) I was able to have the option to not install the update.
If you are seemingly able to keep postponing it, I wouldn't think it'd just some day go on its own. Although you never know, I'd still doubt it though if it'd be giving you the option to choose.
I kind of like the latest version. At first I was hesitant, but it added a little camera shortcut item to the bottom of the lockscreen. Also gave more customizable options for the lockscreen in general (like adding other icon shortcuts to other things if you'd like instead of having the camera shortcut). And other than that my call quality seems a little better since. And if you have music on your phone, when the phone is locked it displays the whole album across the whole lockscreen as it's playing instead of in a small section like before.