I recently spoke with a project manager. He was concerned about the product managers handing off the requirements to the development staff.
He was right to be concerned. Handoffs don't work. The more people think they are done with “their” part, the less likely you are to receive/finish a great product. That's because no one can tell what they really want until they see it.
The more often the requirements-generators see the product as it's being built, the easier it is to modify the product. The more the developers see the testers test the product, the easier it is for them to incorporate that feedback into their development.
A successful product requires everyone to participate fully throughout the whole project. That means you can forget about people coming off this project to start the next one. That's because the people who are supposed to come off the project need to continue their work until everyone is done.
Handoffs don't work. Collaboration does. Keep everyone on the project until it's really done-done-done.