With Google Reader as an API devs had a way to get historical data on practically any RSS feed going back many years. That ability will be lost/gone forever. Even if Google sunsets the reader app, I wish they'd keep this data source open. Its hugely valuable and I don't think there is any alternative to it.
I think that having cached all this data on their server over the years of their own free will, they've put themselves to be in a position where they have a somewhat fiduciary responsibility of keeping this data alive and open.
