Change could be led by current leaders who are inspired by new ideas (which may come from someone or something else) or who realize (or are shown) that the current direction or the existing state of things just is not right or is not working.
I think it is somewhat disingenuous to assert that the situation can change but those who are leading the situation cannot. To suggest that change only comes through revolution (replacing current leadership with new and different leaders) does not allow for the Eureka! moments or the "oh, my God, what have I done?" moments. We have plenty of evidence historically of leaders changing their politics, position, beliefs and so forth, and in many cases that is exactly what makes them leaders, as opposed to those who are intransigent or stubborn and go down with the ship instead of finding a new way to save it.
And there are plenty of examples of leadership changing, but nothing else does.