the AFSB will be based on the the MLP "frame"
It's a possibility. another possibility is for a much larger ships based on a container ship frame (Maersk has thrown around their S-class quite a bit). No matter what the design, NASSCO will probably be the ones to get the contract for the AFSBs, if only to keep them ticking over for the next five years until the Jones act fleet starts needing further replacement and the AO(X) program kicks off.