I'm still curious if it will work out for U.3 as a direct drive interface. From a lot of my discussions, most workhorse server SKUs leveraging Granite Rapids or Turin will be transitioning to EDSFF. This leaves U.3 relegated to low-cost platforms and flexible storage nodes. That means direct attach U.3 will not evaporate, but it's obvious the bulk of SSD development in the market is focused on EDSFF form factors. I imagine a lot of general purpose SSDs will be moving toward E3.S 1T, as the design is built to almost directly replace 2.5" disk designs. Meanwhile we're already seeing E1.S 9.5mm designs replace M.2 card designs in servers today for boot volumes. E1.S 9.5mm is definitely larger, but not by much, and you can't install it in a lay-down slot like M.2, but in exchange it can handle power dissipation around 20W. in other words, it has absolutely no issues handling any of the current M.2 Gen 5 SSD designs.
Fortunately, since we're really discussing an electrical interface here, there are already E1.S -> M.2 conversion modules on the open market. HPE is currently using their own for their Gen 11 designs as they transition to EDSFF. The M.2 Card goes into the carrier, and it presents an EDSFF interface for the backplane. The backplane from a home enthusiast perspective is an open market. We'll see server designs leverage MCIO for density reasons, but there's no reason ICY DOCK and similar companies can't use Oculink, or any of the existing SAS compliant designs like U.2/U.3, mini-SAS HD, Slimline SAS, etc. for 1-4 drive designs to make the connection from backplane to system board or controller.
That's all a lot said to get to the point that I think direct attach U.3's universal interface support is going to be too little, too late in the home market. I think the benefits of SAS / SATA / NVMe on the same interface will be lost on most home enthusiasts who are really purchasing for the highest speeds possible. I think what does have potential is E1.S 9.5mm, and E3.S 1T, both in the form of "carriers" since EDSFF needs a backplane to connect into vs. a direct cable connection. What I could forsee happening is these M.2 Gen 5 SSD designs getting "enthusiast" variants via dropping it into an EDSFF carrier, where now there's no issues dissipating the heat. That to me makes way more sense compared to trying to put giant heatsinks on a module sitting on your motherboard. This also has the benefit of SSD manufacturers not needing to make an altered physical SSD SKU. "Regular" users get the bare SSD and heatspreader, and the unit throttles. Enthusiast users get the same SSD but with a thermal pad and dropped into an EDSFF carrier. Now the SSD can support sustained use without throttling. Seems like a more likely outcome to me when considering a business' interest in keeping hardware variants to a minimum.