RSS needs to be integrated into email clients, not web browsers. RSS's "notification" use cases are closer to email, even in the terminology ("subscribe"). If there was better support in email clients, RSS would see more use for things like ecommerce shipment notifications, website and ecommerce "newsletters" (which often get marked as spam when sent as email) and the like. The user remains in "control" then, unlike email spam, because they can unsubscribe by grabbing the feed anymore. Reach statistics would be more accurate too (for the same content that was traditionally delivered via email).