So either Blizzard create a very different Demon Hunter class that bears little if any resemblence to the existing model (making the entire exercise of developing a class to cater to players who want a DH totally null and void) or it creates a class which shares a large degree of overlap in both toolkit and theme with Warlocks, which will cause Warlocks to be angry at the DHs for stepping on their territory and DHs to be angry for not developing a unique class identity.
Which of these two options strikes you as viable?
For me...the answer is neither. Blizzard gains nothing by labelling an entirely new class with no in game history "Demon Hunters" and it is likely to actively avoid ticking off players by designing a class so alike in theme and feel to an existing system. Once we add in that DHs don't bring anything new to the game, that their theme and niche is already filled, and that there are other options Blizzard can explore instead, DHs as a standalone class seem very unlikely.