Katie, a nursing degree will certainly give you something to fall back on should you ever need to, given the current shortages of nurses world-wide. You could keep your nursing registration current by doing some agency work at various times throughout the year.
Whilst airlines may not necessarily look more favourably on nurses per se, the skills you will gain in nursing could certainly transfer across to work as an FA - in particular, quick assessment of a situation, ability to remain calm under immense pressure, very sound communication skills, ability to relate to people. At the end of the day however, there probably isn't a lot of point doing a degree you're not interested in, particularly nursing. It can be a hard slog and to be any good at it, you really to be dedicated. If you're heart isn't really in it, then perhaps something more related to tourism/marketing/public relations/hospitality might be better suited.
Just a thought.
M.