In our small aircraft wheel shop, attached to my last hangar set up, the specific greasing of the bearings was strictly applied and itemised on the wheel build sheets (preferred manufacturer had a red colour); the bearings stayed with the wheel and a dummy retainer long bolt with plastic dustbin shape wheel protectors keep the assy together.
The grease retainer (bonded rubber to metal disc/plate) would also be a contributing factor in the bearings life.
Did I understand, this aircraft had been overnight before the incident and yes brake temps are displayed, but who is looking; on older models they would have a green band etc and most Crew know that after T/O especially after short turnarounds or long taxi, they might leave the undercarriage down for longer to cool the brakes/wheels.
I have had aircraft arrive on stand, (mostly L1011) having had some newly fitted brakes at a previous night stop station and those steel brakes have been glowing hot; despite having a FE with the temperature read out on his panel, not a word over the headset; luckily for them we just divert the ground air con hoses onto those brakes before the fuse plug went.
Conversely I have had plugs blow on wheels, were the crew had not released the park brake after the chocks in signal!
The culmination of repetitive hot wheels would be a gradual loss of bearing grease or properties.
The incident aircraft outer bearing cage and rollers had likely disintegrated than the multi spokes of the wheel outer hub.
p.s. my memories of the Line/Ramp ended 16 years ago and so experiences today might be a lot different.