Regarding Serena keeping the baby if Fred died, I doubt they’d take a living child from a War Widow, if anything she’d be highly honoured.
A Handmaids unborn baby on the other hand, could be reassigned, to a ruling man.
Particularly if whispers it wasn’t Fred’s
Serena herself would surely be reassigned though, “you have been issued a woman” perhaps she and June resssigned together
I can see Serena finally losing it and the last shot of her dying in the Colonies