Hey look, there was a grey horse under there!
She should shed out fine. Emaciated horses grow "starvation coats" to protect their bodies. My filly (sold now) had a coat just like you're mare's is, and while it took longer for it to shed than the other horses, she did shed and had a decent summer coat by early May. This year her winter coat was normal thickness.
(terrible edit- sorry. General idea of how thin and hairy she was...but horses that weren't mine were in the background)
after finally shedding out in May (and growing a LOT)
then this winter - totally normal hair growth.
If you clip and blanket your mare, with as thin as she is, I would think there would be a very big chance of her getting sores. She has no muscle or fat so the blanket would be directly rubbing her bones. Ouch! If you must clip, do a bib or low-trace. I think she'll be fine though personally. I'd actually be afraid of cutting her when clipping at this point.
Everyone in your life is meant to
be in your journey, but not all of
them are meant to stay till the end.