I dunno, EHB uses a 6th bit plane and so would a true 64 colour system. Dual Playfield mode also used 6 bit planes too.
I think he meant the silicon area of adding another 32 colour registers (12 bits each) and supporting logic. Probably 32 * 12 * 6 (=2304) transistors for the registers alone, maybe a lot for the old manufacturing process that was used when you are talking about chips with tens of thousands of transistors in total (does anyone know the transistor count of OCS/ECS/etc?).
There was an OCS follow-up that was never released called Ranger:
http://en.wikipedia.org/wiki/Amiga_Ranger_Chipset that was to support 128 colours and high resolutions. It was cancelled due to being too expensive, but that was mainly due to utilising VRAM - it is a shame that a DRAM variant wasn't made for consumer products.
EHB was nice, but they could have also included a complementary colour mode, where the second 32-colours were the complementary colours of the first 32.
On topic: Personally I think a good start for doing games is to port some of the new C64, Spectrum and Amstrad CPC games that are being made to the Amiga, before porting some 80s arcade games maybe.
