Yes sorry man I went off on one.
But why is it hard for you to believe this rumour? Sure we don't know if it's fact yet, but your basically scoffing at it like "Pah! These guys would never appear in Thor! And if so, only in cameos!"
Why do you think that? The two actors in question have been in terrible films before, Thor is not beneath them.
And it makes sense that Branagh would be after guys like this. As you have said before, with a relative unknown as the lead, the big names have gotta come in as supporting roles.
But yea I agree, not De Niro for Odin. I'm thinking Ymir.