ORIGINAL: 2007HemiCuda
As of today no ones knows if you'll be able to buy a new Challenger in two years, so buy now or buy used. Perhpas a 2010 Challenger with a 6.4 will be available...perhaps.
I think the 6.4 is a longshot at best. I seriously doubt we will ever see it. A merger with GM and we will be lucky to see the Challenger hang on through the 09 season.