That's a bit silly IMO. If you've removed the way that those viewers like to view your content, even if they like you, they might not find a suitable replacement in their eyes to the tool they previously used. I have over 200 feeds in my RSS reader that I "consume". If that reader went away (which it is), then I'd probably pay attention to 10ish. Does that mean that I only "care" about those 10? Of course not. I like to monitor the others for headlines or keywords. Just because I don't read every one every day does not mean I don't care. And, when my reader goes away, I won't be back all b/c the medium I use will have changed.
It depends. If you use GReader to read 10 RSS, you can move to FB/Twitter/Mail newsletter.
If, like you or me, use GReader to read 200 feeds, you will find an alternative that suits your needs. Or code it, be it a full RSS parser, or just a greasemonkey addon to change feedly appearance.
Because you care about reading your news, one way or another.
Edit: one thing is special in this case: GReader users are more "power users" than usual. So we are not talking about TMZ site going down. That's why I think that people who really care will try to find an alternative.
I suspect any real competitor in the rss space will provide an instant import via the zip of bookmarks / feeds / etc soon anyway.
I'm just worried about an Android app that can fill Readers roll. I use it for reading webcomics since I can swipe left or right to move through my subscriptions, which is much more efficient than any other means to browse them on mobile.
The ones whom really read your RSS? Or maybe you will gain 10000 twitter followers on July 2? On maybe double your daily visitors?
Visitors who care will still be there. And it's the visitors who matters.