Michael Bisping will defend the UFC middleweight championship against Dan Henderson in the main event of UFC 204.
You didn't read that wrong. The year is still 2016. Michael Bisping really is the UFC middleweight champion, and Dan Henderson is really still fighting at the age of 46.
In fact, Henderson's 46 combined with Bisping's 37 is the oldest title fight that doesn't involve Randy Couture, per Reed Kuhn of Fightnomics:
With 83.7 years of combined life experience, this is the 3rd oldest UFC title fight pairing, and oldest not involving Randy Couture #UFC204 pic.