I wrote up a quick little piece to explain that Alfine Di2 is an indication of the significance of electronic shifting to Shimano's long-term plans for ALL markets: http://goabloc.tumblr.com/post/15674222833/the-future.

The TL;DR: Shimano thinks that eliminating cabled shifting in all of their products as soon as they can is very important. They see it as every bit as big a deal as they saw indexed shifting in the early 80's. And indexed shifting is what established Shimano's complete dominance in bicycle components.