Quick update- I talked to Mike at Norco today, he confirmed that a 24-bay chassis *is* still in the works but apparently hasn't been finalized yet. He noted its been a challenge stuffing 24 bays into 4U, and I pointed out Supermicro's already done it and quite beautifully, so its NOT impossible and many people would be interested since the higher count multiport SATA cards tend to come in multiples of 8, meaning 4 ports on a card can go to waste in a 20-bay case unless you want loose drives sitting inside the case. I may start a separate thread to solicit design feedback and feature requests since Norco is open to it.
I also noted many people would be interested in an expander, basically a drive cage - for people that just want to add lots of drives to an existing system. Example take a full length server case like a Norco 4220, cut it in half and leave leave the front half (drive bays, backplane and fans), and leave just enough room in the back to add a power supply. Add a couple SFF-8088 connectors on the back and it's heaven.