Nintendo wouldn't let Gamefreak do that. They would encourage them to delay the game and make it better. Worst case scenario, I could see them releasing some pokemon as either free or paid DLC later in the game's life.
And I just don't think they would ever go under 90 new pokemon. That's just too much of a stretch. Also, where's the proof? Is this like the SR and weather nerf that some guy just randomly said?
It would be at over 100 new Pokemon if digimon evolution isn't implemented. Give new evolution to existing Pokemon like Mawile, Absol, Jynx, Farfetch'd, Delibird, etc. Plus, it means less crap pokemon and more quality pokemon. 4th are doing it right in terms of new pokemom.
Mega evolution is possibly the one of biggest mistake GameFreak made. Obviously, it is unbalance, along with complicated dual moves. How are you feeling if Mega Lucario sweeps your team with no effort?