The cambelt is due every 100,000 miles on the TDDI.

It is an unusual setup as it is half chain half belt. The chain goes from the crank to the pump and is obviously sealed. The belt then runs from the pump up to the cam.

I've got a 1999 TDDI with 155k on it and love it. I cannot see the point or need to change it.

The only biggy could be a sudden failure of the Bosch VE fuel pump. That is a risk you have to take. Note that big miler VW/Audis use the same pump. It is a luck of the draw type thing but they do sometimes fail. Sometimes.