It looks like this is a bug in the stats, so people are probably still receiving email updates, at least for the time being.
http://feedburnerstatus.blogspot.com/2012/09/known-issue-subscriber-counts-and-stats.html

You can still get the email address of all your subscribers via the Publicize tab. It might be a good idea to export all of those email addresses now, while the data is still available.