If you're asking about hardware support for DE... like, on the Kindle or Sony Reader, etc... I wouldn't hold my breath if I were you.
It seems like the most the hardware companies only see their own proprietary formats as in their best interests, and don't seem to be too hep on supporting anything other than their own format (and perhaps PDF, as it is already ubiquitous). So they're not jumping on the ePub bandwagon... and DE is essentially a whole new interface for files, in formats they don't really want to support.
I don't expect any hardware makers to support DE until after they wholeheartedly support ePub, when and if they see ePub as within their best interests. Even then, if they don't see any benefit to their hardware for the DE interface, and their hardware will run ePub files without it, they might not support that.