Having owned 11 turbo vehicles I can tell you that I have yet to experience a "turbo" specific failure problem. My Syclone had 73k miles on it when I blew the engine up, and I took the turbo in for inspection at a turbo shop. The prognosis was that the turbo was in great shape, and the bearings and seals were both fine.
As a previous Audi S4 owner (twice) I know that the early cars had some compressor impellar failures that weren't pretty. Other than that most of the car makers engineer a lot of durability into contemporary turbo vehicles. Think about all of the VW, Subaru, Mitsubishi, and Volvo turbo engined cars running around the streets. I am certain that most of the turbo-related maintenance problems are due to maintenance neglect, or the owner not properly managing warm-up and cool-down.