At 125k I did most of this stuff. My observations...
V-belt idler and tensioner all still good but I replaced.
Fan support started to make noise and I replaced.
Fan clutch good and I did not replace.
Water pump and thermostat good but I replaced.
Transmission oil was still good, but it is about time to replace (had to replace the radiator so I got to sample it).
PCV valve was kind of working but not very well and had lots of deposits, so it was a bit overdue for replacement. It was the original. I replaced.
Coolant was very good, but I replaced due to radiator replacement.
Radiator recently started to show the crack line but it still had a few thousand miles to go. Truck lived in PNW all its life so that might explain the radiator longevity. I replaced it.
About the engine air filter ...
I did not replaced it. I have one of those inexpensive devices installed on the air box (K&N Filter Minder PN:85-2445), that measure and display the maximum vacuum inside the box, basically letting me know when it is time to replace the filter. I periodically blow the filter with air (opposite direction of the airflow), rotate it 180dgr, and each time I do that I reset the indicator. Every time I see a big drop on indication. At this time, the filter has more than 30% to go (it was replaced at 90k). I know they are relatively cheap. I also live in PNW and do not drive on dusty conditions or off road. I also do not drive a lot in a big city with bad air quality. So my experience is not your typical 200 owner experience.