When I was looking for an RSS reader on my iPad the vast majority synced only with Google Reader. It was either that, or use their account and be fed news instead of telling them exactly which feeds I want to read.
That and they make you read them in huge squares instead of lists. One thing Google might do is automatically download all Google Reader users' data using https://www.google.com/takeout/ and allowing those apps to access the data. I think I'm seeing Gmail go too for G+. Maybe not GCal because of GGlass but right now most of what's free from Google I'm seeing it gone in 3 years.