While Some See Philip Glass as Half Full

Today is Philip Glass' 75th birthday.  One might claim that he is the last major symphonic composer.  Provocatively, one might even claim that he could be the final great symphonic composer.  With film scores becoming more and more dominated by popular music, could we be seeing the end of an art form?  Every college and university has a music department or conservatory where composition is taught.  Every major city has at least one orchestra.  So, it is not that symphonic music is not performed. With so many teachers and students and surely advances in pedagogy and understanding of method, why aren't we seeing a string of new Copelands and Iveses?  There is some contemporary music performed, but it tends to be boutique.   It is the 17th through early 20th century stuff that brings in the crowds, well, that keeps the orchestras in business at least.  Why don't we have contemporary big names in symphonic composition?  Will Philip Glass be the last great symphonic composer?