That might be the initial impulse of many persons. However blogs, like Wikipedia, are only as reliable as their sources. To the extent that the blog cannot cite an accessible news source, the credibility is diminished.
I think you are right there is a real possibility of an online subscription causing loss of online audience, as well as physical subscriptions. That is why newspapers have been very gingerly approaching this solution. But you can bet that every major newspaper which currently doesn’t charge for online access will be monitoring the outcome of those which do make the changeover.
The success of The Times (of London), the New York Times and the Wall Street Journal have encouraged second tier newspapers to follow suit. Whether less prestigious newspapers can make the pay model work, I think, remains to be seen.