Now I'm going to propose a more likely future scenario. Imagine you are on another planet and there is a software flaw that needs to be patched. Do you want to have to beg some billionaire millions of miles away for the privilege of modifying the code, or do you want the ability to fix it as soon as possible? If its a time-sensitive issue consider the consequences of having to fumble around with deploying signed patches, or installing a new key and updating everything to work with the new key.
None of these trust devices are perfect, they might leak data that can be used to infer keys through side channel, or can be physically inspected, etc, I think we can all agree they are not perfect. So if the security model breaks down with physical access then the only adequate solution is physical security. Putting your faith into some crypto function that will be obsoleted by time is not a winning defense. It's also possible the keys may have been obtained by a malicious adversary, rendering this mathematical security layer ineffective at best. If I can install new keys, then an attacker can also install new keys. If the imperfect security measure causes more problems than it solves, then its worth rethinking.
What problem would it ACTUALLY solve in this scenario? Maybe it could be used to mitigate a breakaway civilization by only allowing patches through remote update channels, keeping new outposts fully dependent on Earth. Potentially at the cost of real lives if that update channel is broken somehow. Though someone always figures out a way to break the lock :)
Please I don't want to hear about some hypothetical dissident of a tyrannical regime, they should have destroyed the device before capture if they had any wits. The regime would probably be forcing its citizens to run fully validated stack anyway and would be all up in their business for (red flag) installing their own key instead of government approved key... Corporate security? Lol do you think your petty secrets are worth restricting humanity by normalizing imperfect security measures? Some of these corporations need to be kept in check somehow, they have too much power already.
The only future I'm on board with is one with a robust well tested software ecosystem controlled by its users/operators/owners, not a careless conglomeration that prioritizes the well being of it's shareholders, or crushing its competition.