I wonder if this has any connection to the DC graphic novels being exclusive to the Kindle Fire at launch. It sounds me me like those books will be in KF8 format and since it's only going to be initially supported by the KFire, that's the only way they will sell them. It also explains why they're not going to release them for BN at least initially, KF8's support for panel view may not be something that epub supports yet. (I'm sure it could - but I don't think it does now.)
The good news is that this implies that any other device using a Kindle App may eventually get access to those GNs once the app supports KF8.