Maybe rock has nothing more to say for Bobby Gillespie - as a jaded, millionaire rock 'star' whose band (who I have dearly loved) haven't produced anything interesting for quite a while. His statement might have more to do with his lack of relevance than the real state of music.
I seem to remember hearing that someone from Decca Records told the Beatles that guitar music was 'on the way out' in the 1960's; that rock had become jaded just before Nirvana and grunge hit the airwaves; that guitar bands were passé, then along came The Arctic Monkeys et al.
New types of music will come along, and this is a good thing, but that doesn't mean that styles of the past (jazz, rock, country, classical, disco etc...) die out - they continue to evolve.
RAWK RULEZ!