Most of the alternative TAM concepts do have CD-ROM drives, unless what you mean is that you wouldn't be interested in a "retro vintage mac!" product that didn't have one.
None of the other retro/vintage/mini/nostalgia rerelease products are at all "expandable" or have a way to load software, so there's a very good chance a commercial version of this thing wouldn't either.
The 3/6 slot thing is funny to me because, yeah, a fourth slot would've gone a fair bit. The review of one of the upgraded Beige G3 models from mid-1998, I believe when Apple launched mass-customization of those machines and its online store, is particularly telling because the reviewer outright and literally spent most of the time asking "what if I want all of this different stuff?" The answer ended up being that the blue-and-white would have much of that stuff built in and would greatly relieve slot pressure overall, with firewire, usb, 10/100 ethernet and a better stock graphics card, in a slot. (One of the cited upgrade options at the time was a better video card, another was a separate DVD decoder, which Apple ultimately added to some Rage128 variants and which the Radeons could do, and then the later G3s/G4s could just do in software, and there was going to be a DVD-having Beige G3 variant with DVD decoding on the personality card, which Apple never released as far as I know.
In my mind, the fact that the absolute vast majority of G3/G4/G5/MacPro systems we find today have zero or perhaps one slot filled is testament to the fact that it in no way hurt Apple or the Mac platform as a whole that a six slot Mac was canceled. It absolutely would've been annoying if you had $4000 or so you were planning on dumping into a machine in late 1998 or early 1999 and then suddenly the blue-and-white G3 is launched and half of what you bought or wanted as upgrades is just built into the motherboard, and the graphics are themselves removable giving you some more flexibility the beige lacked. But, that represents a certain number of people at the upper echelons of Mac usership who were at a certain point in their own upgrade/refresh cycle at that particular moment (everyone else got a lot longer out of their beiges, bought blues, or it didn't matter because they didn't want to cram 5 cards worth of things into a 3-slot system).
From a business and financials perspective though, I can absolutely see why Apple did it. Of all their different product lines, I absolutely bet you the six-slot machines sold the least. It's of course a given that the reason for that is almost certainl because UMAX and PowerComputing were selling equivalent machines, often with better stock equipment, without shenanigans like being out of stock because Apple insisted on bundling a Zip drive.
In addition, while it's entirely entertaining to think of the prospect that it's Apple's bad comeback at the community for not what happened with the clones, there's also the fact that the 9700/PowerExpress was a planned 604 machine, but as I'm sure you know, the G3 utterly creams the 604ev in benchmarks. I've posted benches between my 8600/300 and my Beige G3/300 before and in integer performance (again, what most day-to-day computing tasks rely on) the 300MHz G3 is at least two times faster than the 300MHz 604ev. At FP, they are matched.
In 1997, this match-up could have been a 604ev@360 and a G3@266, and to a certain extent I imagine that's why the Beige G3s directly replaced the 7300/7600 and 8600 along with small business 4400 and 6500 configurations and the 9600 was left to preside over the lineup for a little bit longer, but they (Apple) absolutely had to have known that it would've looked bad once 1998 and 300MHz G3s rolled around.
Almost anything that could have preserved the excuse for the 9700 to exist (multi-processing in OS X, significantly faster frequencies on the 604ev side) was far enough off that if the 9700 had launched at, IDK, 400MHz, a 333MHz G3 would've looked like a much better deal and it would almost certainly have been a bust.
All that said: There's no particularly good reason, other than parts commonality and not wanting or originally planning to do the engineering work, why a 6-slot version of the Gossamer (or Yosemite, for that matter) motherboard couldn't have existed. Apple could hypothetically have put it in the same case the 8600/9600 used and continued the personality card infrastructure directly into the top end model, and sidestepped both the lack of a 6-slot machine (which, again, I'd say there are approximately a dozen or two people who still care about, all likely on this site) and the fact that the G3 just ended up smashing the 604/e/ev, performance-wise.
For all of that, I really do suspect the 9700's cancelation was last-minute and for the reason that the G3's performance ended up being much better than expected.
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