Motherboard manufaturers should split more PCIe lanes for SSDs.
Right now you can connect old NVMe drives through USB adaptor (claims 800MB/s throughput).
It’s all about cost really. Threadripper offers increased I/O capabilities at a reasonably modest cost. It makes sense to have standard components designed to cater to standard needs +-2sigma. So if you want substantially different capabilities, you either go for the niche tier of building blocks, or augment your standard box to solve your problem. How much storage do you want and why?
If I understood BRiT correctly, he wanted the modularity of connecting SATA drives. That’s not going to happen as long as we slot the SSDs directly into the motherboard. But why? Assuming we still want the cheap standard component base system, if it is because he doesn’t want to waste the capacity of old M.2 drives, well plug them into an external cabinet that connects to USB or thunderbolt, which allows 10 20 or 40 Gb/s respectively. (God I wish USB4 was universally adopted
right now). If you want to build something extremely fast by RAID-0 over a lot of drives - well that can’t be done in current PC architecture no matter what connecting scheme you use, so that cannot be a justification for having more M.2 connectors.
At the end of the day the current standard compromise is reasonable - you can connect a couple of fast drives to the motherboard, and if you want to connect more without needing the highest bandwidth, you plug them into your I/O standard of choice. That should serve +-4sigmas or so. Beyond that you go to more server oriented hardware platforms.
I think manufacturers like this. There is nothing really stopping them from implementing a system where they provide 32 PCI-lanes and you insert PCIx4 drives as you buy them, but it would add fractionally to the cost for everyone, and they would loose some high margin business selling dedicated hardware to a niche that can pay more. (Kind of like 10Gb Ethernet.) The SATA ports provided serve those that desire tens of TB in their box, but the trend is away from that to remote storage, either in NAS form if you’re oldfashioned or cloud storage.