The book of Isaiah is in its totality a book of prophecy for the little span of time called the end days or covered in the catch phrases 'In those days' or 'In the latter days' etc.   Yes, many of the events are historical but they serve as a type of shadow of what is to be.  There is nothing new under the sun. 

 Isaiah used history to inform his latter-day audience of what it coming.   In the days of Isaiah Egypt was a super power with political and religious leaders who were both failing and bumbling and the people had become wretched and full of mischief.  This is the setting for todays superpower - The United States of America. 

 I use the book of 2 Esdras from the Apocrypha and the book  of Isaiah to paint a picture of what ill be in America's future.