Given the fact that we've seen no evidence of such updates previously, and rather we've seen Apple take many steps to protect privacy and even seen NSA leaked slides detailing how they need access to PCs to read iPhone backups, I think it's extremely unlikely that they would ever take the risk of pushing an customer-wide software update.

If you are worried about being specifically targeted, you shouldn't use an off the shelf cellphone at all, and this discussion is moot.