On the 3.2 and 3.5s the water pump or tensioner usually fails before the belt does. Mine all got changed at 88k miles because the guy I bought it from did all that plus new clutch and windshield before selling it (the reason I bought it even though I didnt want black).

What's the deal about time ? Some of our VXs have low mileage but the 99s are getting 11+ years on the timing belts. Do they need to be changed ?
Rubber does break down and dry out over time so it may not last as long as far as miles. But the biggest enemy to rubber is UV which isnt an issue with t-belts. Can probably go another 11 years lol.

I wouldnt change the t-belt without changing the water pump. I just dont like doing work twice. If I just did the belt, the pump would fail on me 2 weeks later.