Commodore has just announced the A2232, a seven-port, RS-232 serial card
for the A2000. In combination with the machine's native serial port, this
gives 8 ports to attach terminals. CBM has also noted on their
documentation that more than 1 A2232 can be attached to a single A2000.
This would allow at least 15 ports, possibly up to 36. The A2232 has an
on-board processor to alleviate the load on the Amiga's 68000, but I would
bet that an accelerator would be something you'd want eventually.
Note that custom software would be necessary to *DO* anything from the
remote terminals, since no windowing software would work. Of course, if
your terminals are Amigas, then anything is possible. <grin>