"She must be famous"; "She can be famous"; "She may be famous"; "She might be famous"
I believe these can be ranked in terms of the speaker's sense of the likelihood.
She must be famous. How could she not be famous?
She can be famous. If she wanted to, she could become famous.
She might be famous. Nothing stands in the way of her being or becoming famous.
She may be famous. For all we know, she's famous. But who knows?