Micah's already used for girls, I don't see why it wouldn't eventually become more popular for girls than boys.
I would have assumed
Micah was a girls name, the only male
Micah I've never heard is a really awful local news anchorman named
Micah Ohlman on LA's KABC. And honestly, it sounds like one of those names that someone made up, I know it's biblical, but it sounds made up.
I'm just not a fan of soft or gentle sounding boys' names, anything that ends in an 'ah' sounds like a girls' name to me.