Recent figures showed that the best selling games of 2008 were FIFA 2009, Mario Kart Wii, and Grand Theft Auto IV. Perhaps the most obvious thing that these three games have in common is the fact that they're all sequels in long running franchises.
But when you look back at the biggest, most hyped games of last year, you start to notice that the majority of them are sequels too. Not only that, but many of the forthcoming releases of 2009 are also the next iteration of a series. Sure, you get the occasional new IP, but even some of them are reboots of far older games and movies, bought into the 21st century.