Hopefully Apple allows storage upgrades in the future- and I think this confirms the Mac Pro will at least allow storage upgrades. A step in the right direction for Apple!
The current Mac Pro with a T2 chip basically functions the same way. Cannot put two '1' modules into a single system. have to DFU from a second Mac to do an "upgrade". There isn't much "new direction" here. Mac Pro parts came after supply catch up with demand. But the Studio is marked by Apple as "User not accessible". So not particularly good expectation management to suggest they are going to do a 180 degree turn here. Probably not.
As for the future. Apple didn't do much to apply this DIY upgrade parts supply chain for the iMac Pro. [ These NAND daughter card scheme first appeared almost 5 years ago and yet folks keep acting like Apple did something 'new' in 2019 and 2022. ] The glue locking down the rubber strip protecting the case screws is suggestive they aren't going to do parts for Studio . The Studio seems more likely to get treated like the iMac Pro 2017 than the Mac Pro 2019 . [ even more so since Apple is treating it as an iMac replacement for the moment. ]
Long term still only have the initial SSD controller ( embedded in the M1-series SoC). Not particularly likely that its ability to deal with later gen NAND chips will surface... So will increasingly will be limited to NAND daughter cards that Apple won't make in high volume in the distant future.