You can now get a single chip containing 2 MB static ram, I would like to see a board using a 9900 running at one of 2 speeds selected by the clock on/off external instructions, 2 MB Ram, no cartridge port, no GPL roms, no GROMs and no storage of data in the extremely limited amount of video ram, socket for F18A, sound chip(s) PS/2 sockets for KBD and Mouse 2 DB9 sockets for joysticks, a circuit to provide 300 interrupts per second for operating system functions, 2 serial ports, 2 parallel ports and designed to fit in the PEB replacing the firehose, 32k ram and serial port cards.
A new multitasking graphical operating system with mouse control would be written for the machine, taking advantage of the fast context switching possible on the 9900.
I know "it will not be a 99/4a" but you already have several of them and choose to use emulators instead.
Also 2 PATA Disk on modules for storage.