Ikea cheesegrater is very funny - and looks like it's real - someone at Ikea knows Macs and has a sense of humor... I wonder how many folks will get it (do most people know what a current Mac Pro looks like?)
On the gaming Mac idea, I sincerely hope not - not because I mind the hardware being out there, but because getting top games to perform at an e-sports level requires compromises in the operating system. If Apple says "fine, we'll build the hardware, but we won't make concessions to games in MacOS", they'll have a nice gaming PC that is substantially slower than Windows alternatives - even if they offer the latest Nvidia cards and have a good, stable driver similar to their current AMD driver.
Getting games to really perform requires three things Apple won't do, and I think they're right not to.
1.) Lower-level hardware access. Games don't want to go through documented OS calls when there's a faster way of doing things... Unfortunately, that both inherently destabilizes the system and is a boon for malware authors who also want to access the system at a lower level.
2.) A tolerance for hardware run close to the edge. It's well known that Macs are somewhat slower than Windows PCs using the same hardware on low-level benchmarks. They're sometimes faster in real-world tasks because some parts of MacOS are more efficient than Windows, and Macs aren't as burdened by security software (necessary) or bloatware (not necessary, but installed on many PCs). Part of Macs' lesser benchmark performance is due to sleek designs that are not as well cooled, but it's also because Apple runs hardware conservatively (overclocking friendly processors not overclocked, for example). Even if there were a Mac with Nvidia graphics, it would run them at stock clocks that essentially no PC gaming card uses. They all have mild factory overclocks, and the stuff competitive esports uses is significantly overclocked.
3.) A willingness to use unstable drivers - closely related to the hardware close to the edge. Apple's highly stable AMD driver is essentially a workstation driver - optimized for stability instead of performance. What it's closer to than anything else is Nvidia's new Studio driver program aimed at creative types. Nvidia themselves say that trying to game on Studio drivers incurs a performance hit (I think they say it averages 5-10%). Apple would either have to keep making Studio-type drivers and accept that hit or accept the instability of a gaming driver.
I suspect that, because of items 2 and 3 alone (if top games came to MacOS and somehow performed well despite the OS, eliminating item 1), a gaming Mac using Apple's known philosophies would be about 15% slower than a comparable gaming-optimized PC. Once you add in the highly variable effect of the OS forcing slower, but stable ways of doing things, it could be anywhere from 15% overall (where the OS doesn't matter) to 30% overall (where a highly desirable hack is eliminated).
The alternative is that they make the stability concessions to games that they have refused until now. This makes Macs less stable for all of us who either don't game at all or game only casually.
I suppose that the third option is an Apple-sponsored esports league, where everybody has to use the same Apple hardware and the performance hit is just part of the rules (baseball banned the spitball, after all). I suspect they'd have to offer huge prizes to lure serious competitors away from higher-performance leagues (how many top real-world drivers choose to drive Formula 2???)...