I doubt Apple is basing the decision on that; I think it's more likely that there simply isn't a market at all, or at least none significant enough to justify it. While people wanting a more powerful Mac Mini may be fairly common on a forum like this, in the wider market I expect we're a pretty small minority; at least the Mac Pro is a high margin device and can also push sales of the latest and greatest pro software (if Apple keeps developing it at least!), but a better Mac Mini model or something in between isn't likely to make a ton of money IMO, even though I'd jump at the chance personally.Apple doesn't see the market, probably because they were burned with the Cube.
So yeah, I believe that any hopes of the Mac Mini returning to a dedicated GPU or actual graphics cards of some kind is pure wishful thinking, and people hoping for it should know better than to do so by now
Besides which the progress of integrated GPUs is proving that machines like the Mac Mini don't really need dedicated graphics to still perform well; the Iris Pro runs pretty damned well, it's just a shame you can't buy it for a hackintosh or I'd have been running one for several months by now!