I would love to see a Chol Hamoed trip gemach. Many of the trips that I have gone on (and are no longer of interest to my kids) would still be a real treat to someone else.
Often, you have a family trip that is suitable for 4 out of 6 kids, and the other 2 would have lots of fun on one of our trips. It would also allow me to send 2 of my kids on another trip, where they’ve not gone to yet (and for whatever reason, I cannot go on).
Truth is, it will never fly in a big way beause working out the details (gender, hashkofoh, ect) would be too challenging. But its still a thought. Maybe to limit it to a shul by shul basis, so at least the hashkofoh part is settled.