Q: What would be the impact on students if a project ended by just ceasing work without any of the suggestions in this chapter?"
If a project just abruptly ended, or maybe kind of dwindled off, students would definitely be cheated; essentially missing the whole point of the project in the first place! First, students would feel like the work they did didn't really matter. That it wasn't good enough, that it wasn't relevant to them. Secondly, students would be a whole lot less likely to participate in another project in the future.
Some students might feel relieved; you weren't serious about doing all that work. Just dropping a collaborative project without the conclusion is showing your students that you were, in fact, not serious about it!! Why then, should they be?! Not to mention, it would be horrible professionalism and could really hurt your reputation in whatever community the project was involved in. Has any school ever been asked, but not responded, to a request to be acknowledged for their work?
Let's say, however, that you do finish the project. Grades are given, you begin a new unit of study in your daily lesson plans. This is cheating the project too! You and your students put all that work into that project, and now... what? Without reflecting, editing and sharing your experience, with other teachers and with your students, the project won't really ever end. I went back and looked at some of the earlier FC projects, and I can see where and how things have changed into the format that it is now. So, in that way you will never remain stuck in a rut, so to speak.
I really liked the idea of private reflection groups within schools. A lot of time, I personally, find it much easier to sit down and write to really reflect and organize what I have to say to someone to best convey my message. So yes, private/shared reflective groups within learning communities are the best possible way for this sharing to take place on a professional development level.
