After giving the matter some additional consideration, I've decided not to have the BS work done proactively.
I'm at 195K miles now and the car will be 5 years old in June. I'm thinking/hoping that if I were going to have a problem in the BS area it would have surfaced by now and that the problems being seen now are limited to a specific lot or lots that I'm not a part of.
Also, while there are definitely problems in the field, we don't know yet how widespread this really is. I know there is another thread in this forum where we're attempting to gather that data but I don't know whether we'll ever be able to gather enough data to have a statistically valid population to draw conclusions from.
I know that all chains will eventually break but perhaps by the time mine lets go, I'll be ready to let go of the car. I had hoped to get 400K out of it and that may or may not happen but it's a goal, not a requirement. Should I end up with a broken part, I'd have to make the repair ROI determination at that time.
While it's possible this is a design defect, it's also possible that VW had already decided to make some improvements in the BS area due to manufacturing cost reduction goals or for future functionality but which have no functional impact on this particular engine. The current failures could just be a matter of coincidence. I work for a computer hardware manufacturer and I've seen stranger things happen.
Also, if VW knew there was going to be massive fallout from a known design defect, wouldn't they have positioned more parts in North America ahead of time to head off the inevitable complaints that would result from cars being out of service for extended periods due to part availability? Maybe I'm giving them too much credit.
I feel like if I spend the money now I'll just have that nagging suspicion that I spent the money unnecessarily. I know others would rather not have the nagging suspicion that they're driving an engine that could fail at any moment and I totally understand that. It's just that with the data that's available so far, the former suspicion is carrying more weight for me than the latter.
As this situation evolves my opinion may change. I just hope it's not due to first hand experience!