If you get the same news, and you were happy with what you were paying to get high quality news (you're not buying a sheet of paper, you're buying the news), then what's the problem?
Why should moving to digital mean reducing the price versus print?
Perhaps the NY Times should keep the margin difference as profit, helping to restore their financial condition from the recent disaster it has been, so they don't have to go crawling to Carlos Slim again. Building up their financial position would assist in their independence as a news source.
Perhaps the NY Times should put that margin back into the business, and create more / better content, thus more than justifying the price staying the same.
Either way, the argument in favor of reducing prices just because of cheaper distribution, is not inherently a good one.