Yes and no. You are probably hoping for an instant update containing all the new Pokemon the moment the game comes out, right? That's a big no. Maybe up to a year or so after it comes out, if not longer? Most likely. They will be implemented, but not anytime soon. That being because Gammal and others are still working on balancing the other 493, not including the new ones. Not only that, but they would have to be sprited, animated, etc. Then, you have to tack on the coding for them following you around and a whole slew of other things.
TL;DR, not right away, but eventually.
