2025, Q2: Airbus remote execution vulnerability discovered. (Did you just assume 100% reliable HW+SW, on Hacker News? That's some serious handwaving...)
(Note that I didn't mention anything about webservers, or Internet; are you sure the in-flight entertainment systems are separated from the control network by anything else than a firewall rule? See other embedded systems, and how secure they are. Start with...IDK, Toyota's gas pedal code, see how well such safety-critical code was written: https://users.ece.cmu.edu/~koopman/pubs/koopman14_toyota_ua_... )
Why would you think that the parent assumes 100% reliable SW? Having SW more reliable than humans would be enough reason to replace humans with it. This does not seem impossible to me.
Well, the problem with current state-of-the-art flight automation is that it can deal well with routine, repetitive tasks. What it fails at are corner cases (cf. US Airways Flight 1549), and self-diagnostics (sensor readings are inconsistent with current flight profile, e.g. Air France 447). In such cases, what you need is intelligence, not automatics.
This makes your argument another case of "let's assume we have strong AI; then pilotless aviation is easy-peasy." In other words, one of your unstated assumptions is still firmly in the realm of science fiction.
Full disclosure of the vulnerability revealed by the Google team zero implicate Windows update mechanism originally devised to allow flyers to play online with their premium ultimate+ Live account. (where would we be without a bit of Microsoft hate? ....)