used to say that sth might happen or might have happened in a particular way, because nobody really knows :
Who's to say we would not have succeeded if we'd had more time?
used to say that sth might happen or might have happened in a particular way, because nobody really knows :
Who's to say we would not have succeeded if we'd had more time?
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005