I had experienced a change in PM once in my career, and the resulting events were similar to what jlw23 had mentioned. We had a get up to speed meeting with the new PM, which I attended with my team lead. In this meeting, all team leads discussed the current status of their tasks. The new PM was quickly filled in on how the project is progressing, and all members talked about whether current aspects of the project should be changed based on observations, such as getting more resources for certain tasks or changing something up. Once all details were out, a new blueprint was created for the project based on the issues and observations the team leads mentioned, as well as what the new PM deemed should be done. In the end the meeting was a “get up to speed and optimize” meeting for the new PM.