ARM with Thumb 2 has moved close to what an enhanced 68k would be and it doesn't have any trouble selling. I think we would be a little more powerful and easier to use while Thumb 2 is a little more power efficient.
You can't dislodge ARM, even Intel will struggle taking them on.
Dreaming that you can, when you can't even duplicate what Motorola was doing twenty years ago, is just going to dislodge you from achieving anything.
If you look at the history of AROS, you'll see there were similar problems with the AmigOS project that preceded it:
"Several small groups' of Amiga users on the internet coordinated their efforts to create an open-source Amiga operating system that was not controlled by a incompetent, restrictive parent company. The most popular of these was the AmigOS project, which gained brief attention in Amiga User International during 1994. However, bitter flame wars on the feasibility of such an OS tore the project apart and the dream of an open-source Amiga OS disappeared.
During the fourth quarter of 1995, Aaron Digulla attempted to get the project moving again, by sending an RFC (Request For Comment) to the AmigOS mailing list. He suggested that a minimum specification list should be defined, allowing the creation of a basic open source OS. Once this stage had been completed, the group could decide if multi-processing, resource tracking, and other features missing from the official AmigaOS, could be implemented. After some discussion it was decided that the group should create a portable version of OS3.1. The Amiga Replacement Operating System was born..."
Only when they stopped arguing about how to do memory protection etc and just focus on OS3.1 compatibility did the project even start to take shape.
Natami still has a long way to go & it's going to be expensive. FPGA arcade has avoided a lot of the problems by only adding the bare minimum.
Also because mikej isn't trying to create his own computer platform, he doesn't have to try to control what is put into the FPGA. Natami on the other hand needed to lock out anyone from coming along who could write better VHDL.