Sure, sharing and friends will be replaced by Google+ variants, but to me that sounds like a good thing. Instead of copying articles and pasting them into Google+, I'll be able to just hit share.
Those features of Google Reader (friends, sharing) were useless dupes of other features present elsewhere on other websites (Facebook, Google+, Twitter). I already have enough friend lists to maintain as is.
I used Google Reader for reading, and that is it. I don't care that they integrate it with Google+, although to me it makes sense. I just care that they remove the useless separate list and ecosystem.
I'm in nathanb's boat - I share articles with people within Reader, but I don't want those to be pushed to G+. Similarly, I don't want to be forced to read other people's links through G+.
And they said they said they are integrating the two better, so I'm assuming its possible for them can make the sharing between the two fairly fluid.
My bigger concern is the disconnect in sharing. Are they turning Reader into a one-way service, in that you share items to G+? It would seem incongruous to share things through Reader, but then have to go into G+ to see what other people shared.