Because a steak today is better than a cow next year.
Beside that, there were only rumors, even if they were official rumors spread by Nintendo's chief Satoru Iwata, about this new console known as Nintendo NX.
The thing is, it was said that new info would be revealed in 2016, not that the console would be released in 2016.
There is also the death of Nintendo president, Satoru Iwata, to be considered as a major delay in this new console plan of release.
Concluding, the most reasonable reason for the lack of a "next gen" Pokkén tournament, is the lack of said Next Gen.
Also, in the news video I linked in my question ( this one ) they would have mentioned something about a new console coming out in 2016, since you know, 2016 is right around the corner and most sales come from excited fans.
So there is also that to consider.
Hope this helped buddy!