[JimD]

The main thing I would worry about from not changing the fluid will not be noticed until it is too late. As the fluid begins to break down, it's lubricating qualities are reduced and bearing wear will go up. I believe the same fluid as goes past the gears and bearings also cools the clutches. That heat load will make the fluid degrade more rapidly than in a manual where the clutch is dry and outside of the transmission. Bearing wear will not make itself known in the first 100K miles. But if you drive it long enough, you may need a complete rebuild where you would not if you change the fluid.

I have changed the fluid twice in my manual so far. I have about 81,500 miles on my car. I cannot see anything about a DCT that would make me change it less often.