Firstly - would love some clarity. The WiFI functionality of the R5 II and R1 is tri-band WiFi 6E, so 2.4GHz, 5GHz and 6GHz. If it is, then it's likely a significant overhaul of an existing product, so could be an R7 II given the speculation of the market positioning for a budget professional sports camera use-case. The R7 II at a high frame rate would make a very useful camera for additional remotes, as a fleet of R1 bodies would be costly, but would definitely be a viable use case and would demand good network connectivity, eg, 6GHz to overcome loaded 2.4 and 5GHz bands in stadiums or performance venues. If so, it's likely this was identified during advisory/meetings/early product development stages and would have likely been decided independent of the R6 III as the typical users of that body likely don't have a high performance file transfer use case. The R7 II's closest competition in my mind would actually be the OM-SYSTEM bodies, and would be a really good place to drop in a global shutter which could see serious interest in the camera.
What would an R3 II have that the R1 doesn't? Other than a global shutter, it seems like an odd product. Any other features, and Canon would be looking a bit silly with the R1. Perhaps there is a high resolution alternative to the R1, or a higher quality sensor with a slower readout speed but with an increase in DR and/or better high ISO performance? I find the R3 gave me better low light results (and had more latitude for shadows to be pushed) than any of my low light images from the R1. So maybe an R1s? I'd swap my R1 over for that in a heartbeat.
The Canon 1D Mark IV only got to see the winter games in 2010, as it was superseded by the 1DX in time for London 2012 so short lifecycles for pro series cameras aren't unheard of; it's possible a large agency has put the screws on Canon to make with the global shutter to prevent a switch to Sony, to get the results and workflow they want for the games. The R3 looking like a sore thumb in the lineup is also ripe for replacement.
Some have suggested the EOS RC, or a compact EOS R. I would have expected Canon build this product around the R6 III given what other camera manufacturers have gone eg Sony with the A7C II based on the A7 IV. But what if Canon want to put the guts of an R5 II in there instead, to target a more premium market segment eg potential Leica shooters and pair with a revised 50 1.2L and a 35L without the VCM's shortcomings? I'd expect a dual-band WiFi chip rather than tri-band to keep size and power consumption reduced, but it could be a tri-band chipset with the 6GHz band disabled. That's my other theory, given that Canon would likely want to keep the firmware stack consistent.
The R1 was announced nearly 18 months ago, so the bigger question is why the R6 III still running at the older 802.11ac standard? Did they strike a good deal on the older outdated 802.11ac silicon to keep the prices down? The A7V has WiFI 6. I would be wary of anyone releasing new products in the here and now with outdated WiFi chipsets.
My money is the R7 II first, potentially a revised R1 with a different sensor second, a compact R5 II as a third and a distant fourth will be the phoenixification of the R3 product line (and I don't see another R3 until the R1 gets some sensor tech that makes it look less like a sports camera and more like the no-holds-barred days of the 1Ds series).