it (all) depends
The possibility or likelihood of some outcome depends on one or more unspecified factors. A: "So, would you be willing to join our company?" B: "Well, it depends—what kind of salary are we talking about?" Is it legal? Yes. Is it ethical? Well, it all depends.
it/that (all) deˈpends
(informal) perhaps; possibly: ‘Would you marry him if he asked you to?’ ‘I might. It all depends.’‘But is it right to send people to prison?’ ‘It depends what you mean by right!’