More than anything, it's probably just Warner Classical cutting back on new projects. Also, Barenboim has many musical interests other than Mahler. That's a healthy thing! If Barenboim wanted to record a complete cycle, he would have to do it with an orchestra that would be willing to make their own downloads and/or cd's. Either that, or get a smaller label to record him with a relatively low budget orchestra. In Germany, government subsidies are being cut back all around.