I think most of their products they support long term so long as they're not failures:
- Buzz no one used after a while
- Wave was hype, but died in no time
- Reader is really the only one they dropped but that's not because it was a failure. Google just didn't want to in that service anymore as an aggregation site.
As for Keep, all I can say is this is Google's attempt to jump into the Evernote/OneNote territory. This is the other category of items for Google. Copycat apps. Kinda like Google+? They won't succeed in terms of being the best, but just wanted to join the fray. Who knows if it'll survive or not. I would be worried that this won't succeed and then get killed off like other services, but somehow I think it'll stay. The other similarity is Google Drive. Box, Dropbox are huge. Amongst Mac users, CloudApp is amazing. I don't see how Drive's really a leader except maybe for the document sharing/collaboration aspect.