I love the idea of having that information readily available, but I don't think it will ever be a banner spec. Three numbers is two too many and who wants "density" when you can have "MEGATRANSISTORS"? I know, I know, but marketing is what it is and I think it's better to lean into it.
Of course, and I agree that marketing traction matters. I should have said this is an idle hope that some of these fancier metrics get published/leaked about TSMC/Samsung/Intel processes rather than that they become the metric. I do think MT/mm^2 or whatever is a strong candidate to become the thing. "megatransistors" is an exciting word.