This would almost certainly be Far Cry 4, which Ubisoft has teased would be revealed ‘soon’. Far Cry 3 propelled the series back into favour after the so-so Far Cry 2.
The original Far Cry was steeped in sci-fi whereas Far Cry 2 removed that element and went to Africa against an arms dealer. Far Cry 3 moved back toward the original.
It’s unclear what Far Cry 4 will involve - if Ubisoft will keep it going towards more sci-fi/supernatural elements or whether they’ll try to keep it realistic. ”It’s a great brand,” said Ubisoft’s Tony Key, referring to Far Cry 3’s reception, ”and now it’s got the recognition it deserves, so we’re clearly going to make another one: more on that soon.”
Ubisoft may reveal the next Far Cry at E3 in June given the huge attention it gets.