those who are real teachers, will commit even if they get married. whether or not it works out is in Hashem’s hands but they will commit.
(there is nothing wrong with an inexperienced teacher, there is a lot wrong with a girl who is teaching because she has nothing else to do til she gets married.)
as far as starting a career? really? these girls can get jobs as reading tutors, floating subs, permanent subs, office work, secretarial work – all within the same school building without it interfering with a class if she leaves.
Teaching girls priorities and a sense of commitment would be wonderful for klal yisroel. certainly better than what they are learning right now…