Simply put, this "paid content" model is a direct translation of the good old news paper subscription model. Others, like Forbes, are relying on advertisements and insist on showing you a full blown ad before you browse any content. Its annoying to say the least. The modern web user has grown accustomed to the presence of ads, however, the relevancy of the ad matters as much as the article its wrapped around. When I'm reading a political opinion piece for ,example an ad about "How to Speed up your PC" is not exactly relevant or welcome. A blind reliability on external ad providers may not be good enough. I am not saying that NY Times, Forbes, the Guardian are not going to last, their journalistic value is immense and cannot be debated upon. What they need is a better way of making money out of their content.
Strong social media integration and micro-payments may be the answer. Simply monetize the "like" button. Let visitors to your site register for free, and all content is open. If a users clicks on the "like" button next to an article he may be asked to contribute some money, a really small amount of sum (as low as 10 cents) that people will not bat an eyelid before saying yes. Micro-payment providers will play a big role in the model, although convincing online contributors to start monetizing through micro-payments is proving to be tricky. An excellent article on PaidContent highlights both the promise and the challenges of this model. Maybe the answer is BitCoins? (Peer to Peer online currency, no central authority or bank). If we can get rid of credit cards and just deal in online currency, the process of making the actual payment could be simple and seamlessly integrated into your online experience.