Pokemon Z is not officially revealed yet and most likely will not be called Z, but something else. It's also expected to come out sometime in September-November 2016, just as almost all other games have so far.
As for the starters' typing I would like to see are a Water/Dragon (basically a sea dragon, similar to Gyarados, but looking more like the Japanese water dragon {or Yamata no Orochi} or Lernaean Hydra) on with Water Absorb [immune to Water, x2 weak to Dragon and Fairy], a Grass/Electric (I'm thinking about something like a large hound-like Pokemon that looks really bulky) with Thick Fat [x2 weak to Poison and Bug] and a Fire/Poison (something with toxic flammable fumes and flames to cause explosions) with Levitate [immune to Ground, x2 weak to Water, Psychic and Rock] or Fire/Ground (a lava serpent/leviathan) with Solid Rock [immune to Electric, x3 weak to Water and x1.5 to Ground)] or Fire/Steel (a partially metalized Typhlosion-like Pokemon with hot molten metal dripping) with Filter [immune to Poison, x1.5 weak to Water and Fighting and x3 weak to Ground]! All of the ideas are focused on having each one with as close to two regular weaknesses as possible, with the rest being balanced out by the stat spread!