How many miles and/or commuting seasons will a modern internal geared hub last? I've been considering drive trains on a utility / commuter bike.

The Shimano Alfine internal 8-speed hub is on several bikes I've liked. I've also heard good things about SRAM and Nexus hubs.


I ride in a wet / nasty winters / fairly flat environment here in Minnesota.
I'm partial to lower gearing if it meant more reliability or lower
cost.
I don't need max efficiency
All other factors are secondary to durability in my eyes.


As I’m not current on how much maintenance can I expect a modern internal hub to require, and how long will it last before needing to be replaced. 

What are expected or actual lifetime / maintenance needs of modern internal hubs?
I bought a 700c Jericho hardtail in 1997, which came with a Rohloff 14 speed internally geared hub. I used it as a commuter for five years, at least 150 miles per week, 50 weeks of the year. That's 37500 miles. Even assuming I took a week or 2 out in there for whatever reason, call it 35000 miles. After that, I continued to ride it one or 2 days a week, for less strenuous rides. I have just sent it back for its first major service, other than lubing and cleaning the external components. 

The Rohloff is a ridiculously burly hub. The Alfine, or the i-Motion9 would do well to match half that performance. But I'd say based on people I've sold bikes with Nexus or Alfine hubs, and how rarely we see them for service, and how much more rare it is that they need major service, that 20000 miles is not too much to expect.

The Shimano and SRAM hubs are both user serviceable, unlike the Rohloff, which should extend the useable life significantly also.

I was trying to find any formal service interval information, but both SRAM and Shimano say that aside from cleaning off the external parts, the hubs are "well sealed" and the service interval should be "long".

Sheldon Brown's site also says, "Service should be quite rare on these well sealed hubs."