Who could take Mountbatten's later Combined Operations role?

What would Mountbatten's death in 1940 change when he would otherwise become involved in Combined Operations and Dieppe?

His later appointments would go to someone else, but Churchill's willingness to promote a junior officer makes the replacement and subsequent decisions impossible to identify confidently.

Mountbatten's death in 1940 would remove the officer Churchill later chose for Combined Operations. That appointment involved promoting a comparatively junior captain, so normal seniority gives little guidance about a replacement. Churchill could choose a more senior officer or elevate another junior one. Vian is raised as a possibility, but the suggestion is immediately treated as unlikely. There is no confident successor from which to reconstruct the later raids or command decisions.