That said, it seems the probability of a catastrophic AI takeover in humanity's relative near-term future (say, the next 50 years) is low (maybe 10% chance of happening). However, it's perhaps significantly more likely in the very long-run.

50 years seems like a strange unit of time from my perspective because due to the singularity time will accelerate massively from a subjective perspective. So 50 years might be more analogous to several thousand years historically. (Assuming serious takeoff starts within say 30 years and isn't slowed down with heavy coordination.)