This makes more sense if the phrases “ideological players” and “professional employees” swap places in the sentence. That aside, it says what I’ve been trying to say about the next American presidency better than I said it.
Cheney and his fellow travellers have created a zero-sum reality in American politics. They have played hard-ball with the civil service and the military. The opposition will have a difficult time not acting as if we are under a winner-takes-all system. If they fail to do that, the professional employees who have been completely replaced by ideological players will undermine them; but if they do clean house, the imperial pattern will become entrenched.
The imperial pattern was already there. What seems to have been broken are the institutional restraints on it.