I wonder where the Amiga would have been today if those chips had been sitting on one or more easily swappable boards like what most of the PC did.

What seemed to sink the Amiga in the long run was that to go from OCS to ECS or AGA you basically had to buy a new computer.

But a PC could go from EGA to VGA by swapping out a card.

Never mind that the first 3D accelerators were pass through concoctions, where the VGA card had a short cable run over to the 3D card that in turn was connected to the screen.

The big box Amiga's did get graphics cards with decent specs. The problem wasn't so much that, but that the vast majority of the Amiga volume was the low end machines. You'd never get an Amiga500 or A1200 style machine with card slots usable like that at the time. The big box Amigas sold too little, and the accelerator cards were equivalently high priced niche products.

That, and of course that Commodore management consistently messed up and delayed the better options.

What is a real shame is that Hombre didn't get finished before he bankruptcy [1]: A 64 bit 3D graphics chipset with an integrated PA-RISC and DSP, coupled with an AGA-Amiga-on-a-chip for backwards compatibility, and with Windows NT compatibility (back in the days when NT ran on multiple hardware architectures; though at that time I probably would have thought Commodore had sold it's soul to the devil if I'd seen the Win NT compatibility).

[1] https://en.wikipedia.org/wiki/Amiga_Hombre_chipset

I still have an original 3DFX Voodoo Graphics somewhere that worked like that. Alas, it didn't do any sane from of OpenGL, so eventually I just used it to show X on a second monitor, via a full-screen texture. It worked astonishingly badly.

Now completely unusable, of course, like its Hercules cousin, because it was an ISA bus device.

It wasn't the lack of slots and cards, it was the hardware was too magical and hacky. Basically it was over-engineered so much it couldn't evolve.

People made code that depended on those hacks and magic. If the coprocessor doesn't work the exact same way in the future then everything breaks. That's fine if it's doing something simple like displaying a big array where each byte was a pixel or RGB value because you can easily make that backward compatible. Instead it was doing things like running code between scan-lines and using 5 bits per pixel.

A new display chip would basically have to include the old chip in its entirety just to be backward compatible. All the Amiga hardware worked like this.