Will there be an assassins creed 4

Yes, the story will continue where it left off in Assassins Creed: Brotherhood.
Desmond Miles will return with his parkour abilities to find the infamous "Apples of Eden" and stop the solar flare that will destroy the earth.
There is a rumor that the ancestor that desmond will visit this time, will take place in the 1800's or during WWII. It has not yet been confirmed.