Is D being used/backed by a major software company or a major open source initiative? Looking at the trends so far, seems like it takes the backing of a giant for a programming language to succeed.
Sociomantic, Symmetry and Weka.IO are large very heavy users. Symmetry has supported development with an "Autumn of Code". The backing is much more diverse and its been that way for a long time.
Disclaimer: I contract to Symmetry.