Yes, I feel that there will be new gameplay mechanics in this installment, because Johnny is unlike Niko. Johnny is a gang member (just like CJ was in San Andreas or Toni was in LCS), Niko is a freelancer (just like Claude and Tommy, or more like Vic Vance). The features that were missing from San Andreas, they didn't fit in Niko's story arc. As for Johnny's, it totally fits seeing as it will all revolve around him and his biker gang. So, I presume they will make a comeback?