How can people run out of idea? Most ICOs are about using, enhancing, and integrating technology in our daily lives. Our current technology is not yet fully developed and people are endlessly seeking to improve technology and our daily lives. So, I doubt if people will run out of ideas and ICOs will end.
You have a point there but we are still humans we have a limit, someday sooner or later we will be tired and run out of Ideas this is inevitable