Early this year, Warner Home Video pitched the idea and sponsored the "Total HD" format, an attempt to put both Blu-ray and HD DVD content onto the same physical medium. The obvious advantage for retailers and manufacturers there was the need to only stock or carry one type of disc. Unfortunately for Warner, the idea isn't panning out as well as they'd hoped and as such they are ditching those plans.
They are not abandoning it totally, merely putting it "on hold", but once an idea gets shelved it is rare we hear about it again. The issue seemed to be both technical and financial in nature, with the disc being difficult to manufacture as well as the disc itself costing quite a bit more than a typical one. While manufacturing techniques may improve, with an apparent lack of interest in such a medium they have no incentive to continue. Only New Line Cinema joined them in this endeavor.