In my opinion there is little or no direct pay off. EG does having NHL really prevent any Leaf fans from turning up to see the Argos or watch themn on TV? I don't think so.
However there is an opportunity to see more column inches devoted to the CFL if only because there is no Habs/ Leafs Canucks etc there to hoover up the inches. No bad thing for the League but let's not hang our hat on it.
I agree the effect will be that with no NHL the CFL will have no other pro teams in their cities in which sports fans and writers can focus own. A fan in Montreal may be a bigger hockey fan so if given the choice of watching an NHL game to a CFL game they may choose the NHL. With the NHL off the board now they no longer have the choice.