If this gains wide usage, it could be a boon to RSS adoption. Users could eventually learn to think of websites as collections of changing content, so they'll have less difficulty accepting the use case that RSS offers.
Some people might even think RSS is introduced as an enhancement to this Google feature.
(Or maybe this implementation will become so solid that RSS becomes unnecessary, but I doubt it.)
Understood, but I can imagine a website displaying a button for "Get notified when we add new information" or something to that effect. Personally, I'd love to see more these buttons on local government websites, which are notorious for not having RSS feeds. So people might begin to use Google Reader upon discovering this new feature.
Some people might even think RSS is introduced as an enhancement to this Google feature.
(Or maybe this implementation will become so solid that RSS becomes unnecessary, but I doubt it.)