I'm playing Devil's advocate here a little, but I suppose the trouble is what happens at the latter end of the curve.
When we're down to 12 sources, what then? Supposing they need to drum up revenue to support doing the research once done by thousands of others, so as to give us accurate and factual news, they might consider charging for their content. Once they do, let's say the public decides they will go get the content for free by reading blogs or aggregators, which provide handy summaries of the news, alongside helpful (if biased) interpretations. What then?
If the dying-off trend continues, all we're left with is partisan news which gets its funding from something other than doing good research and writing quality articles. Or we're reading the blog posts of the relatively-informed, and trusting them to abide by some kind of journalistic standard.
That's not really a good thing, now, is it?
Good journalism costs money.