Right, so I was hoping to last for the last year of the current gen and to not open my PS4. I was okay with the noise even tho sometimes it was launching in the space.
Problem came with the Modern Warfare. That thing just sent my PS4 as a rocket right away, specially just in MP menus. There was a patch recently and yesterday I tried to launch the game only to end up straight up crashing after 40 minutes in menus due to overheat. When I decided to try Single Player, I had a prompt that PS4 is overheating. Add to that that whenever I tried to launch CoD Store just to see what's there, my PS4 crashed all the times straigt away.
So yeah, I decided to open it up and blow through the thing. To my surprise, thing was almost clean. For almost 3 years of use you'd expect some stuff inside, but it was like there's nothing to clean. I saw some dust from the heatsink side that you can't really see, but that was it. My PS4 is in office and we have some kind of airblow machine and I decided to aim that thing to the heatsink and oh boy, some stuff flew away. At that point I was pretty suprised that there were chunks of dust after seeing it clean on the inside.
After putting it together I straight up went to the Call of Duty MP menus. Yeah, that thing is still loud but it's nowhere near to previous state. It's not launching anything to space, it's not crashing after minutes in menus. Ultimate test was the store that was crashing my Pro all the time. Not a single problem with that thing.
So yeah, if you have the screwdriver and like 20 minutes of your time - just do it. It's not rocket science, it's fast and it has results.