I would say that, ridden at the same speed for the same number of miles, a hub dynamo should outlast a bottle dynamo by a large margin, AND should provide a higher quality riding experience during that time (no whine, no wear on tires, and much less drag).
However, all hub dynamos are not created equal, neither are all bottle dynamos. I've never used a bottle dynamo long enough to wear one out, although one (a Miller) did lose it's shiny chrome plating.
If a hub dynamo does burn out (which seems very unlikely)....the magnets are in the rotating hub, the stator windings would be in the stationary portion NOT laced to the wheel? So windings could be replaced without relacing, if you could order a new part from the makers.
Having said that...if you only ride at night for 5% of the time, even a bottle dynamo will last a very long time, and is very easy and cheap to replace if it does fail.
Or, you could just use rechargeable batteries and LED lights.