Synthesized answer
The practical implications of superintelligence revolve around its potential to shape the future [1]. This is because extreme levels of machine intelligence, or superintelligence, would be in a position to do so [1].
What happens to humanity, and even whether humanity would survive, would depend on the goals of such a superintelligence [1]. The provided passages do not offer further details on other practical implications.
Synthesized from the book passages below. Chat with the book on Feynman for follow-up.
From the book
Title: Superintelligence by Nick Bostrom Description: This profoundly ambitious and original book picks its way carefully through a vast tract of forbiddingly difficult intellectual terrain. Categories: Computers Pages: 353 Snippet: Extreme levels of machine intelligence - superintelligence - would potentially be in a position to shape the future. What happens to humanity, whether humanity would even survive, would then depend on the goals of the superintelligence.