Some aspects worth considering, though I'm not sure how it all pans out: GRRM no longer publishes under Random House. He publishes under Penguin Random House - a company formed in 2013 (after the publication of ADWD) through the merger of Random House (Bertelsmann - controls 53% of the merged company) and Penguin (Pearson PLC - controls 47%). Pearson, a publicly traded company, has been hurting after suffering losses in their North American educational products division (small violins playing). Bertelsmann is a privately held company, financial figures are hard to come by.

A couple of things with that - The 2013 merger created the largest book publisher in the world. If any publisher has the purse strings to pressure GRRM, or any author, its them. They're the ones who just splashed out $60m on the Obama book deal.

Also, with the investor pressure on Pearson to increase profits, their stake in Penguin Random House might be a lucrative asset for them to consider selling, at least partially, to Berterlsmann.

Again, nothing concrete about any of the above, just that there's financial pressures brewing at Penguin Random House, and that might push them to increase either the carrot or the stick