Looking at past trends, it seems like Buzz Bee Toys you release more new water blaster models every other year for odd-numbered years. See the iSoaker.com Water Warriors Evolution Tree. The only exception to this happened in 2008 when there was a number of re-releases as well as a surge in the number of pump-action water gun designs. In more recent years, five new items were released in 2013, only two new items were released in 2014, and four new items were released for 2015.
Therefore, going by this trend, we would predict that perhaps only 2 or 3 new models should be expected for 2016.
Of course, some trends are meant to be broken.