If there's a new Tales in 2016 it's probably going to be Fall/Winter 2016 at the earliest, either out of necessity or to slow franchise fatigue they've been moving away from releasing games in the Summer and releasing original games within a year of each other (Xillia 2, if we want to count that as "original", has pretty noticeable reasons why it came out so fast). And I doubt they're going to release nothing in that 20-24 month span.
Whether it's Zestiria PS4 I don't know, but there's almost surely some kind of filler planned for that gap, whether it's Zestiria PS4, Zestiria 2, or an HD port of Abyss or Vesperia or whatever.
And in terms of visuals I don't feel like Vesperia is really doing anything more advanced than Zestiria, I actually think the animation and scene direction makes it looks really awkward in places, but it earns a lot of points for its consistency and simple but pleasant cel-shading. Don't feel the games from Xillia onward have matched that yet.