A rhetorical question asked to show that the person asking it neither knows the answer nor knows who might.
It could be one or the other, or both. Who knows?
Do you think I'll get married before I turn 30? – Who knows, you might never marry.
A rhetorical question asked to express the idea that anything is possible or that anything could happen.
Who knows? Maybe someday he'll finish writing his book and make lots of money selling it.
Since she hasn't studied at all I don't think she'll pass the test, but who knows?
Don't touch that – who knows where it's been?
A – Ally: make sure you have a contact on dry land who knows your location and the time you’re expected off the beach. Source: Internet
Accepting, in 1916, Howells wrote his first major piece, the Piano Quartet in A minor, inspired by the magnificent view of the Malverns ; he dedicated it to "the hill at Chosen ( Churchdown ) and Ivor Gurney who knows it". Source: Internet
Academic study Sami shaman with his drum Cognitive, semiotic, hermeneutic approaches As mentioned, a (debated) approach explains the etymology of the word "shaman" as meaning "one who knows". Source: Internet
A Georgia Senate candidate, Rep. Doug Collins, who desperately wants Trump to like him, picks up on that Kemp, too, even though he probably doesn’t disagree with Kemp’s decision whatsoever, and who knows if Trump really does. Source: Internet
And let's be honest," he said, "I would rather a minister of health is running this kind of show than a minister of cooperative governance who knows and cares little about health. Source: Internet
And it's easy to tell by her hip-swiveling poses that this is a woman who knows how to hold a stage." citation The following year, Austin performed in Ring Of Fire- The Johnny Cash Musical Show citation at the Ethel Barrymore Theatre. Source: Internet