how will life change foe buck and the other dogs now that their lead dog, spitz, is gone?

Now London suggests that Buck is superior to the other dogs because of a combination of instinct and human-like intelligence. The fact that he is on more of a human wavelength gives him an advantage over most other dogs. Buck will now take the lead and run the pack in an efficient disciplined manner. Buck will make sure that there are no fights or unruliness in the pack.