It's similar in that it is such a custom reach-around of an expansion idea that even if it works you still have to start writing support for it in software because nothing that currently exists will be able to take advantage of it.
Support for the 8mb of chip ram wouldn't take much, you just need to make sure that auto config ram doesn't conflict with it. There are several ways that might work. A new kickstart rom, adding autoconfig ability to the hardware itself (you'll need a hook up to gary anyway for extra address bits, hell you could even replace gary) or inject a resident module in the chip ram on boot up that does it.
Most of the other changes would be AGA compatible. Chunky/hicolour modes wouldn't be, you'd need to add the monitor prefs for those & some changes to graphics.library.
Support for texture mapping in the blitter etc is a bit more of a pipe dream and software that used it is more likely to just be demos.
Software support isn't what would stop this getting it off the ground. You'd need to make an fpga to PLCC board with headers to go to adapters for two chips, so just the component cost is going to be expensive. But it would be awesome.