@Mr_Mistoffelees these Arctic fans look ace - I wondered about the tiny fan inside the hub, and now I know
I'd say cooler, fans, case...... I'm seeing a pattern. Stuff that doesn't have electronics ages well. Noctua D-14, Noctua and Silverstone fans, Silverstone FT-02 case. All around 10 years old, absolutely zero plan to change. Best value components ever.
Fans should age poorly, and a lot of cheapo ones do (laptop coolers,cough) but now that it's pointed out, Noctua are pretty immortal. My first LH9i was a rare defective model (made a funny noise), they replaced it for free, the replacement is a decade old now and still silent and performs amazingly.