We have enough time to make up for it. Mourinho hasn't had a whole week match free with the squad yet. Once they are suited to his style we will see improvement.
January could be huge for us as we can improve and push on.
As for the ramifications. I don't think there will be a sudden abandon ship of players. Kane, Son and Alli are players that should playing at the very top, but they are also playing under one of the the best managers of this generation. A summer of Mourinho pre-season and 2 windows could be huge, and we go again with a full year of Jose.