If she isn't freed then spending years or her life in a Sudanese prison could be worse than being executed. Given how women are treated generally we can imagine what they will do to her.
We are rightly horrified at her treatment, but it is based on the laws of the land. You have to assume that those laws are widely accepted or they would not exist. A despotic government can impose laws, but that only lasts for for so long. Eventually either the government changes or the people make it part of their culture and upbringing and want to keep it that way.
It's why we should be wary of Sharia law becoming accepted here. Not because of a few extremists waving signs saying 'death to infidels' - we can deal with them, but because the ordinary people in the street can lead us there one small step at a time.
Ordinary respectable, working class people who grow up in countries with laws like that naturally regard them as sensible and necessary to keep the streets safe. They will tend to vote for MPs who promise stricter laws and promise to cut crime. Hell, I'd vote for that too up to a point, we are too easy on criminals.
It doesn't require that we be overwhelmed by Muslim fanatics or anything dramatic and Daily Mail-ish, it just takes enough people who were brought up to believe governments should 'crack down' on crime and immorality to change the balance and start a slow slide in that direction.
We are already saying that 'some Sharia law is ok' as long as it only applies to Muslim women who live here. That is 'voluntary' of course, but in the real world we know what that means to a woman surrounded by her family.
Gradually we can become accustomed to small changes and our children will regard them as normal.
Or... every time someone says Sharia Law is harmless we can point to a picture of this woman and say "NO!".