I like the idea!

Is it to be some kind of command line-based thing, or will it be functionally more similar to the Classic Mac OS (i.e., more graphical)?

Having something Classic-like with preemptive multitasking, protected memory, and support for more modern applications and peripherals would be incredibly excellent. Perhaps these could be incorporated in a modular fashion, so they can be added or subtracted depending on the needs of the user?

Good luck! I hope you accomplish your goal!!

c