Hi,
the bearing looks pretty well. No visible cause to change.
If the sealings fails it has cracks, or peaces miss in general the grease is gone after a very short time. Also you'll get pitting on the bearing balls after a very short time.
The recommended oil change interval in germany is every 20.000 Km, which is around 12.500 miles. Oil change always means oil filter change too.
In germany a yearly inspection for the car is recommended by Porsche. In general Porsche does a oil and filter change if you'll bring your car in for a yearly inspection. Most poeple haven't done that, because that did make the car very expensive. Porsche charged around 28 euro per litre in 2006.
I don't know if regular oil/filter changes are the solution. There are also other factors like the quality of the seal bearing, over revving of the engine, the overall construction of the engine casing… also daily driven cars seem to have less IMS beering fails…
I'll do a yearly inspection and oil/filter change myself. By only driving around 4.000 Km (around 2.500 miles) a year the oil in my car definetely can't be the cause for an IMS fail.
But i have to say that in the first 5 years i did only inspections / oil and oil filter changes every 20.000 Km.
Regards from germany
Markus