You'd have a hard time setting a monthly price that is acceptable to both consumers and publishers. The New York Times runs anywhere from $16 to $30 per month, depending on which level access you're willing to pay for. The Washington Post is $9.99 per month. You'd likely need to bundle in at least one top publication to sell people on the subscription, and every site you add will jack the price up based on the price they can demand for access to just their site.

I think a better solution be an E-ZPass equivalent for the web. Subscribers add credits to their accounts ($1.00 = 100 or 1,000 credits), and publishers can set the tolls for their content however they want, i.e., 1 credit per article, 5 credits after your 10th article, 1,000 credits for a week on the site, etc.

I'm not convinced that micropayments can't work in combination with other revenue models.