Indexical Obsolescence?

Tightening up the index for Einstein's Jewish Science.  Last item before it goes to the printers.  It will be released in mid-April in both hardback and e-book formats.  If we are moving towards an all e-book world in the next decade or so, will indices be necessary?  With the ability to search for any term you choose, is there still a function for the list of names and terms the author thinks make up the essence of the book?  Is the index about to go the way of the 8-track or does it have some special standing?