Sorry LT its not going to happen on a wide scale for a while. Yes cetrain SF units are using the 6.8 but on a limited basis. I highly doubt that we'll see a main battle rifle cartridge change anytime soon as it would be cost prohibited. To many other items have a higher priority, such as a replacement for the hummer.
For me though, it wont be long before I pick up a 6.8 upper for my Car 15.