My condolences to to the families and friends at this tragic time, my thoughts also extend to the engineers involved as one can imagine the horrors and thoughts they are also going through.
Hopefully the NTSB will be able to come to a finding as to what went so tragically wrong, looking at the NTSB video you can see them examining a relatively intact engine, correct me if I am wrong, but it appears feathered, so they may have the engine of concern that has escaped the worst of the fire.