Indeed, the thing that still risks causing change is Sakuya herself. But shortly, we would presumably run out of energy and be stopped as well, and... that would be that.
>"Ah, that is true. But I find it strange... you're doing this because even things you thought would never change have changed; that those who would never leave, have left. Yet, your solution is to leave as well. To leave the flow of time itself, and become truly and absolutely alone. Is that really the kind of eternity you want?"