I don't see $30/year happening, but I could see Amazon trying $29.95/month. Since their new Kindle is supposed to includes EVDO, that would be pretty simple for them to implement securely (until hacked.)
That is probably where the $50 rumor came in. I could see offereing the Kindle for $50, but requiring a 2 year subscription, just like Phone, Cable, etc. It sure seems like a sustainable business model, you'd need to get a phone company and the publishers to agree to keep the prices down during startup. Heck, I'd be awfully temped to buy one with that model.