I think that producing an entire motherboard is cheaper and easier than doing extrange accelerators.... for example look at our classic ppc accelerators, they require lots of layers to allow all that components to fit in such a small board... an entire motherboard would require less layers and would allow you to use standard northbridges, making an easier and cleaner design. In addition to that memory types change almost with each CPU generation so it makes more sense not to use accelerators. I like the idea of having the cpu in a slot or a simple cpu card like in the Pegasos, but if we are talking of such a big changes in memory types and cpu it's a far better idea to make a new motherboard.
