Do you remember not that many chapters back where God told Jeremiah to tell the people of Israel who had been taken into exile into Babylon to build houses, plant gardens, have a whole gaggle of children and get comfortable because this is where you will be living for a loooong time. But then he tells the people who have been taken to Egypt that they are going to die any day now. Don't get too comfortable because it simply is not going to last. You are going to be destroyed. Well, that is simply because the people who went to Egypt disobeyed God and didn't remain in the land like he told them.
Here, this is a message written by Baruch the scribe for Jeremiah geared much more toward those who had fled to Egypt. He tells the people: "I am going to break down what I have built, and pluck up what I have planted... I am going to bring disaster on all flesh." This is geared directly to Jeremiah to tell the people of Israel who are in Egypt. But he tells Jeremiah that even in the midst of all this destruction he will still maintain and keep the life of Jeremiah in the middle of all this. He will witness the destruction but his prize of war will be his own life. Not sure if that is a super great incentive knowing that all that you love and own is gone. A bit like what we see happen to Job.