So it's not feasible to fiddle with incoming firmware
updates, even with the level of access Relapse gives? I couldn't imagine how such a thing would be implemented. A hypervisor?
The underlying architectures are quite complex but there are some good tech talks about them online. One of the best is by Tony Chen, which covers Xbox One security. It's many years obsolete now, but even that security system wasn't cracked until long after obsolescence. Microsoft have proven you can build an effectively unbeatable security system for general computing devices even though they only use it for games and multiplayer anti-cheat. It seems Sony might have not reached Microsoft's level.
Maybe AI will speed things up by making it easier to find obscure bugs, but design wise the architectures are sound and can work well.