The idiom "we'll cross that bridge when we come to it" means:
1. We will talk about that problem if and when it happens. This means that we will address or deal with a particular issue only when it actually occurs, rather than worrying about it in advance.
2. We are not going to do that yet. This implies that the current focus is on addressing immediate concerns or tasks, and the mentioned action or decision will be postponed until a later time when it becomes necessary.