Below 100 thousand units it doesn't make any sense to have custom silicon. The ARM SBCs are all based on existing TV boxes, including the original Raspberry Pi so you are unlikely to see a development board before a proper laptop or NUC-like desktop is released.

meh. i think the unit count is down to about a thousand. also strongly dependent on what node size you use. 180nm and 350nm are pretty cheap these days. but you're probably only off by an order of magnitude if you're talking about 28nm (which is what the SiFive HiFive Unleashed chip uses.)

but... your point was probably more along the lines of "getting custom silicon is still going to need a market of greater than several thousand," and that's probably always going to be true.

Oof that's steep. Assuming ARM doesn't try to kill RISC-V, I imagine the economics will improve significantly over the next few years. Probably larger than 75% drop for similar specs over two years as the low hanging fruit has not been picked yet... But it's important that there's still demand for RISC-V, which is where ARM might be able to choke it off.