Parmandur
Book-Friend, he/him
A 16Bit game won't cut it, every D&D game would still be compared to Baldurs Gate, Neverwinter Nights(2) or, depending on the genre, Dark Alliance. Anything worse than that will automatically garner a negative reaction from the playerbase.
But the big point is, there is simply no interest in the D&D license any more. Even if there had not been the 4Ed which damaged the D&D brand, most game designers figured out that they can equally well design their own generic fantasy (or science fiction) world and have an equally invested fanbase, full control over their IP and do not have to care about future licensing.
There are some exceptions when licenses are strong and cheap (warhammer) or have a rather uncommon theme (cyberpunk). But generic Tolkien inspired fantasy? They are easy to create. Or you specifically don't do Tolkien fantasy which alone garners some interest in the oversaturated fantasy market.
In short, there is no company out there with enough resources to make a adequate game which has any interest in D&D unless they can get it for (nearly) free. And WotC won't do that kind of deal (yet).
Whelp, which is why WotC is making their own software division, I reckon. Not that they will be competing with Dragon Age or anything, but they will be at least invested.