Quotas are at best a temporary crutch, to help prod people out of old habits. They are best applied early in the pipeline. There probably are fewer qualified female corporate leaders than male, because fewer women get the necessary experience and grooming in mid-level and lower-level management positions. Just as in science and engineering, women (and other underrepresented groups) need to be brought into the field early in their academic and professional careers, so they are aware of opportunities and see them as viable career goals.
As for the willingness of women to sacrifice family life for corporate life, this is a sacrifice we would do better to stop requiring from men. This has less to do with the internal desires of an individual woman (or man), and more to do with external pressures and expectations. The goal should not be complete gender parity in all occupations, but rather complete gender parity in the ability to develop one's real potential, without the artificial hindrances of prejudice and unbalanced social expectations.