Final answer:
The potential outcome if the newsies successfully shut down a paper like the World, according to Katherine, is that they will become the new kingmakers.
Step-by-step explanation:
According to Katherine in the context of newsies shutting down a paper like the World, the potential outcome is that they will become the new kingmakers. This means that they will gain power and influence in determining what news is published and what stories gain attention. This outcome suggests that by successfully shutting down a paper, the newsies will have a significant impact on the media landscape.