Hasbro would want to invest in an already profitable media business (they tried with Dreamworks and LionsGate, but failed); acquiring a money-losing venture that bleeds more cash than Paramount has last year in it's worst year is not a sane investment thesis.
Gaining Legendary gives them literally a fat nothing - they don't own most of their film franchises (Godzilla - Toho, Pokemon Detective - The Pokemon Company, Jurassic World/Park - they are financing the film - Universal, etc.)
So yeah, don't see that happening anytime but Hasbro has been exploring acquiring a media entity, you're correct, but I don't know one that would be willing to "sell" to Hasbro.