Adobe never makes announcements about updates.
Updates are usually about every three months, the last one was on July 28th.
The Nikon D750 was announced on Sept 12th so work preparing profiles for this new model would only have started then.
Hopefully it would be included in the next update when its ready. Your guess would be as good as any other user on the forum.
If you wish to get an idea as to the timeline of raw support for new cameras, lens support and tether support progresses for Lightroom and ACR the link below will provide additional info. Obviously Adobe has a planned procedure in place.