I don't know who needs to hear this. Based on the hubbub on multiple Mac news sites, I'm guessing many. Here are some facts based on knowns and unknowns regarding whatever machine Apple is going to replace the Mac Pro (2019) aka MacPro7,1 with:
1. The RAM will not be separately user-upgradeable; it will be tied to the SoC.
2. There will be no PCIe GPU nor eGPU upgradability or expansion; the only GPU will be the one on the SoC.
Before anyone challenges me with that, make sure you have watched this video from WWDC 2020 (where the Intel to Apple Silicon transition was first announced):
https://developer.apple.com/videos/play/wwdc2020/10686/ (at about the 1-minute mark)
3.
This doesn't mean that there's no point to a Mac tower with PCIe expansion; there are plenty of professionals that need broadcast cards or special video tuners or audio interface boards in their Mac Pro; these things are not the kinds of things you can solve with Thunderbolt 4 or a Thunderbolt 3/4 breakout box. It's just not practical.
4. There's nothing in the referenced video above that negates the notion that Apple could socket the SoC and/or make it user-upgradeable/replaceable. Those of you that have used or operated a 2009-2012 Mac Pro (aka MacPro4,1 or MacPro5,1) have seen a similar concept in the form of the processor tray and backplane. There's nothing stopping Apple from doing something similar here. That's not to say that SoC upgrades likely won't cost an arm and a leg. They probably will be very expensive (assuming Apple goes this route). But it will still be possible to upgrade RAM and graphics this way.
5. The internal SSD on a 2019 Mac Pro is already proprietary, requires a DFU restore of the T2 chip in order to replace the storage; modules become useless when removed from the Mac Pro they came from;
this won't be different on an Apple Silicon Mac Pro replacement either. Furthermore, if the SoC is to be user-replaceable due to being socketed or on a processor tray, the internal storage will need to be wiped when performing an SoC replacement/upgrade. This is how Apple Silicon and T2 Mac Storage works. This has no bearing on SATA or PCIe SSDs; just storage controlled by the SoC.
6. The base model SoC offered for this new Mac Pro will most likely run rings around the least expensive Mac Pro (2019) MPX AMD video card option. This is a safe bet. Less safe of a bet, but still perfectly plausible, is that it also runs rings around the MOST expensive Mac Pro (2019) MPX AMD video card option. This won't fully soften the blow of having the GPU be tied to the SoC and not upgradeable separately from it, but it will soften it for a decent amount of Mac Pro customers.
7. Apple likely won't introduce a dual-socket Apple Silicon Mac, let alone Mac Pro. This isn't a guarantee, but given everything that they said about using two discrete SoCs when first unveiling the M1 Ultra shows that they'd rather take two SoCs and bridge them internally into one mega SoC than go the dual-socket route. They could introduce a totally different technology that makes this feasible for the Mac Pro, but this seems unlikely.
8. "M2 Extreme" may have been cancelled, but it is extremely unlikely that an M2 Ultra, born out of two M2 Max SoCs with "Ultra-Fusion" will be the only SoC going into the next Mac Pro. You can customize a Mac Pro (2019) with 1.5TB of RAM. I'm sure that very few Mac Pro customers do this, but I'm also sure that there are some that do. Apple may not replace the current Mac Pro with a Mac Pro that goes all the way to 1.5TB of RAM, but it's safe to assume that they'd at least try to get halfway there. At best, an M2 Ultra, born out of the highest end M2 Max SoC times 2 would only yield 192GB of RAM. I'm not saying that isn't a ton of RAM even still. But a far cry from even half of the current Mac Pro's maximum. Let's assume that M3 Max is able to offer 128GB of RAM (by virtue of M3 being able to go to 32GB of RAM from M2's maximum of 24GB - up from M1's 16GB). That still only gives M3 Ultra a maximum of 256GB. Apple is going to continue the Intel Mac Pro's tradition of offering an entirely different class of SoC unique to Mac Pro. That's not to say that a "Max" or "Ultra" SoC won't still be on offer. That's totally possible too. There are probably many folks that would be fine with a "Max" chip's performance, but needing PCIe slots for specialized cards. But, you'd probably also have folks that would need to go to Ultra before eventually building a Mac Pro with that next level tier.
9. No, Apple hasn't forgotten about the Pros. In 2019, they released two products that all but outright admitted that they messed up. One was the current Mac Pro. The other was the first and last Intel 16-inch MacBook Pro (the first Mac since the butterfly keyboard to not have a butterfly keyboard and to be thicker than its predecessor for the sake of better performance). They did these moves for Pros. We're not getting another trash can. The "Ultra" configuration of Mac Studio is not going to be the best high-end desktop Mac that Apple is going to offer. You won't see regular upgrades to the Mac Pro. And, per that video linked above (which is to say "per how Apple Silicon is fundamentally designed as a Macintosh hardware platform"), you will not have the level of easy aftermarket upgradeability you had with the 2019 (let alone 2009-2012) Mac Pro. But it ought to still be a decent upgrade and not a trash can upgrade.