Here's how I think this is going to go:
For starters, this theory is predicated on the notion that the forthcoming redesigned Apple Silicon 14" replacement of the 13" MacBook Pro and the similarly redesigned Apple Silicon 16" MacBook Pro will not be using the same SoCs as each other, as might've been assumed before. Also, the notion that Apple separating the 16" MacBook Pro from the 13" MacBook Pro as different products on the website (as well as updating them at different intervals [originally thanks to Intel]) is the start of a greater separation between the two, rather than a further unification.
Here's how this might go:
The 14" MacBook Pro will be introduced this fall. It will have an M2 SoC, which may or may not have higher CPU and GPU core counts than M1, but regardless, be a sizable amount faster. It will feature a redesign, the likes of which, we've been reading rumors about for months now and will bring expandability of RAM to 32GB, 3 Thunderbolt/USB4 ports, HDMI, SD-Card Slot, MagSafe, support for more than one external display, SSD capacities up to 4TB, and a visual look consistent with the rumors. A lower-end model may exist, with give or take one fewer GPU core and Thunderbolt/USB4 Port. Apple will discontinue both the MacBook Pro (13-inch, 2020, Four Thunderbolt 3 Ports) and the MacBook Pro (13-inch, M1, 2020).
At or around the same time, The next Mac mini will be introduced this fall. It will have the same M2 SoC as was just mentioned above with the same specs. We'll get a third Thunderbolt/USB4, give or take the return of the SD slot, give or take a visual redesign, give or take additional USB-A ports. It will also bring expandability of RAM to 32GB and SSD capacities up to 4TB. This will prompt Apple to discontinue the 2018 Intel Mac mini. Apple may also use this time to silently launch the Ice Lake-SP Mac Pro in the current chassis design, if it doesn't release it later on in coincidence with the launch of the Apple Silicon Mac Pro.
In the Spring of 2022, the MacBook Air and the 24" iMac get updated with the same M2 SoC as the 14" MacBook Pro and the Mac mini detailed above on the high-end, and one with a reduced core count on the low end. The MacBook Air gets it rumored redesign to be in line with the 24" iMac a la the iMac G3 and iBook G3. The ports remain the same, give or take the return of MagSafe. The M1 Air might remain on sale for longer as a low-cost option at a lower price point.
At WWDC 2022, Apple unveils the long-awaited 16" version of the redesign introduced by the 14" MacBook Pro. The ports are the same as that of the 14" MacBook Pro, give or take an extra Thunderbolt/USB4 port. Apple also unveils the 30" iMac in a redesign similar to the 24" iMac, except with four Thunderbolt/USB4 ports, four USB-C ports, headphone jack, and 10GbE in the power brick. Both will be powered by the M2X, which features a sizable number of additional cores and/or at faster speeds over M2. Alongside these will be the launch of the Apple Silicon Mac Pro, using a similar, but smaller design from the 2019 model. If the Ice Lake SP Mac Pro hasn't launched by this point in time, it will also do so alongside the Apple Silicon model. The Apple Silicon Mac Pro will be powered by an M2Z, which would either be a special version of the M2X that could be configured for dual-processor/dual-SoC configuration OR an SoC that basically has twice the number of GPU and CPU cores of a standard M2X.
By the end of the opening keynote, all Mac models have an Apple Silicon version going forward. The 2020 Intel 27" iMac will be discontinued at this time. The Ice Lake-SP Mac Pro is still sold for another two to three years. The Intel 16" MacBook Pro is sold until Intel EoLs those 9th Gen CPUs (much in the way that Intel EOLed the CPUs in the iMac Pro causing it to be discontinued). The Ice Lake-SP Mac Pro and the 2019 16" MacBook Pro are the last Intel Macs on the market, for a time, but the hardware transition is complete to the degree that every Mac model will have an Apple Silicon version that is marketed more heavily than the Intel version. (in fact, those two Intel Macs will be drastically de-emphasized, similar to how the still-sold iMac (21.5-inch, 2017) is today.). Hardware transition functionally complete!
Alternate possibility: It's possible that the larger Apple Silicon iMac, the Mac Pro, and the 16" MacBook Pro all have the same beefier processor, but that said processor is of the calibur typically offered by the Mac Pro. The Mac Pro was only substantially separate from the rest of the lineup in the Intel era. In the PowerPC era, the PowerMacs weren't ever too dissimilar from their iMac counterparts (save for dual-CPU systems)