For those loyal customers who have gotten addicted to two-day shipping, an additional $20 is a small price to pay in order to feed that need. On the other hand, a spike in the Prime rate might have newbies shaking their heads. “Too good to be true,” they’ll say. “We knew it all along.”
There's no need to be this vague about it. If you order a certain number of things a year from Amazon, Prime pays for itself. If you don't, it doesn't.