i think she is mortal until she isn't. It's been said she has god hood and even in the descriptions in LOX and stuff she has made the impact of that status so i do see this as her mortal life in the same way i saw hercules mortal life (in general, the myth) as one. A belasco scene i saw posted not long ago actually speaks of it to me where he talks about the celestial consequnces of what killing one of the xmen would mean and he didn't care, to me i assume it was storm. so while she isn't there yet in terms of what one would call a true celestial being i guess i think that is ultimately where her joruney ends and why she holds on so tight to her humanity. i guess i feel based on her history at some point when storm is no longer storm as we know her there is a space in the fabric of the marvel universe where she fits and all her destiny is leading there.