I'd love to have a daily online North American newspaper on the Left.
The question is not circulation per se but _paid_ circulation that makes it possible to pay for reporters, editors, designers, proofreaders, and so on, which even online left-wing newspapers need if they are to rival the depth and breadth, quality and quantity, of the best bourgeois newspapers, rather than to put out just another collection of opinions (of which there is no shortage).
The Net is a great medium for circulating information, but it, due to its ability to negate private property by infinite reproducibility, is a poor medium for making money*, which is what for-profit newspapers are finding out today.
An online North American weekly is conceivably doable, but it will be still difficult to make people pay for professional work.
* Except perhaps for porn and gambling. -- Yoshie <http://montages.blogspot.com/> <http://mrzine.org> <http://monthlyreview.org/>