Bingo. There is no tradition to the 10-year cycle, and no reason they can't deviate from it. It just happens to be how the product cycle fell.
If it comes out 2nd quarter of 2017, they are going to call it a 2018. They want to report strong sales of a new model, and and will get it by adding 9 months to the model year instead of subtracting 3.
The Cherokee should be evidence enought that Fiat is willing to break tradition.