I'd take things back a year:
Still make the A500+, but with an EC020 and 2MB Chip onboard. Maybe add an internal IDE connector too, use this as a sensible intermediate system to run down stocks of remaining ECS chips and A500 cases. Remain compatible with existing edge-connector devices.
Scrap the A600 altogether.
A1200, but this time with a socketed '030 (Offer a choice of CPU speeds perhaps) and with 2MB Chip and 2/4/8MB Fast option. PCMCIA is probably a better option than a proprietary connector on the side.
