I am going to read that article when I go home. You said let's be realistic because of lack of programmers?
No, I said "be realistic" because it's really something of a stretch to suggest that the IIgs would be such an AMAZING platform if-only-it-had-a-faster-CPU that there'd be oodles of reasons for people to flock to it. Adding an accelerator is basically just a brute-force way of working around the IIgs' fundamentally weak graphics chipset; if you're super-optimistic you could say that it puts it level with its competition, it doesn't make it better.
By the way. Just so you know. Someone can add an accelerator graphics hardware that uses the exact same apple //gs famous graphics output, composite or rgb etc but add missing features such as sprites, blitter, hardware scrolling, etc as a new hardware fpga or whatnot upgrade for the apple //gs.
Famous? I only said that it has a bigger palette than the Atari ST (IE, it's 12 bit instead of 9 bit, which ironically would mostly would make it noticeably better at displaying *grayscale* images) and a couple obscure features that make it kinda-sorta better at a very limited set of tasks compared to its generally superior rivals. There's nothing about its video output that's super-magically-honey-sweet compared to any other system of that era; the quality of its TV/CGA-resolution analog RGB output stacks up pretty evenly compared to systems as pathetic as the $219 Tandy Color Computer 3(*1). In short, it's nice for a home computer built in 1986, but looks kind of like garbage compared even to 1987's VGA.(*2)
As to making some sort of graphics accelerator for it that adds sprites and blitters and whatever, sure, it's certainly technically possible that someone could do something like that... but why? It wouldn't be compatible with any existing IIgs software, so for a potential programmer your already tiny target audience of people-with-Apple IIgs-es-equipped-with-CPU-accelerators would shrink further to the subset of those who've also bought this graphics card.
Realistically speaking, if what you want is a IIgs with gaming-oriented graphics accelerator they already made one. It looks like this:
(*1) Sadly there are people that would make the case that the 6809 in the CoCo3 is a better CPU than the IIgs' 65C816. Nobody made any version of it that clocked much faster than 2mhz, though.
(*2) I'll take non-interlaced 640x480 over 640x200 for productivity programs any day; the GS/OS desktop in particular is a real eyeball scorcher. And VGA had 320x200 in 256-simultaneous-colors-out-of-262,144 *on the whole screen* vs. the IIgs's 320x200 in 16-colors-per-line-chosen-from-16-possible-palettes-chosen-from-4096-colors for games.)