I was a Forth enthusiast and read the book in OP (in early 2000's) and followed Chuck's work from afar, but I am not sure what exactly I could do with this chip, given its peculiar limitations.
OK, so first, it has a lot of I/O ports of different kinds on just one chip. In a lab, you could run lots of analogue knobs and many servos attached to just one chip. This means a lot less hardware debugging, which should be a Godsend.
Another possibility is HPC. You can tile a motherboard with these, cool them all down to -50 very easily and cheaply, and then overclock them as you perform number crunching that you couldn't do with a GPU. After all, these cores are truly independent, and can therefore branch independently, unlike GPU cores. That opens the door to a wide variety of algorithms that aren't GPGPU accessible.
yet like said at the beginning, it doesn't stop me from wishing I had an excuse to play with them. Blazing speed with lots of cores, there ought to be some applications that for that sort of parallel horsepower.
I'd love to be able to do some useful work with that, of course.