The merger supposedly would help fight off competition from self-publishers (how?) and give the new company more negotiating heft with Amazon.
And further down in the article it mentions another reason to spin off HarperCollins and merge it with another company.
News Corp. is in the process of splitting into two listed companies, one containing its entertainment assets, such as the 20th Century Fox film studio and Fox News cable channel, and the other housing publishing assets, including Dow Jones and HarperCollins....
One motivation for the split is the flexibility to pursue the purchase of old-media companies that may have turned off current News Corp. investors, according to a person familiar with the company's strategy.