Imagine if you had an Amiga Chipset and you had combined it with a RISC like chip. If you did that in late 70s with 3.5μm HMOS (like 68k). The resulting system would be insane, in terms of performance to cost. You could outperform minicomputers that cost 10-100x more.
The ARM2 like chip and the complete Amiga chipset seem to have less transistors then a single 68k, so the price off such a system would be very low. And we can see that with the Amiga, what really blows my mind is how cheap Amiga ended up being, an unbelievable achievment.
Its seem the issue really was the the companies that had the resources to do that amount of chip design knowlage and finances were not interest in making a home computers/workstation. Workstation ended up being made by startups who didn't have the resources to do so much costume work. Appollo was a split-off group DEC because DEC was not interested in workstations. IBM was just to slow and couldn't really do prodcut design, and we all know how the eventually got around that problem with the PC. Apple for the Mac did try to do one ambitious chip with VSLI but didn't end up using it.
The split between computer companies and chip design company was just to big to get the needed amount of integration, and there was clearly a lacking vision for what home computer could be. Jobs vision for the Macintosh went in the right direction, but really Jay Mine had the right vision, and he had it because he build a computer for himself. He wanted a home comptuer that was fast, had a proper operating system and enough media capability to run a flight simulator software. Sadly manamgent most of the time wanted him to develop a console and later when they allowed a home computer they didn't share his full vision.
But then also actually plulling this vision off, multi-chip costume design with very few resources is just an amazing achievment. And many of the people didn't even have that much knowlage in chip design, there was a lot of competition for chip design people. Getting into Commmodore where they had the actual semiconductor teams to get these designs over the line was lucky, many other companies who could have bought them might have messed this up.
In a perfect world you add ARM2-like RISC chip, a Sun-like costume MMU to something like Amiga Chipset and you move computing forward by 10+ years. In reality the exact opposite won, a 16-bit PC that had basically no costume design in it what so ever.