Don't know about that tamalie...in Roth's eyes Fredo was, like Pentangeli, "small potatoes". Tom Hagen, good guy though he was, was not a wartime consigliere and by extension he was not a wartime Don and Fredo was barely capable of running a Mickely Mouse nightclub much less a multi-million dollar crime empire. I figure Roth was sure that with Michael out of the way it would be the death knell for the Corleone family. He would take over their Nevada interests (after whacking Al Neri) and he would leave NYC to people like the Rosatos...and maybe a young Joey Zasa