What exactly is the question? Is it: “Will Firefox ever again have a control on the Preferences page to completely prevent updating?”
I doubt it, but that’s not an official “Never ever,” it’s just based on the observation that preferences a user might employ to expose themselves to increased security risks have been trending toward reduced visibility.
Switching updates off is not very wise move… while I agree that autoupdates may (in some cases) be quite distractious (esp when doing sth important where you need to focus) and hasslefull…
I personally think that - if I was to chose policy of (auto) updates - what I would do is to place some switch in preferences, but (say) bold autoupdate option…