The phrase "if nothing intervenes" essentially means "if nothing unexpected occurs." There are several synonyms for this phrase, including "barring any unforeseen circumstances," "in the absence of any impediments," and "without any hitches." Another way to say this could be "assuming everything goes as planned," or "provided there are no obstacles." Whether in personal or professional life, it is common to use this phrase when making a statement or plan that is contingent on certain conditions. By using these alternative phrases, you can add variety to your language and avoid repeating the same words and phrases.