We'll see whether that ever sees the light of day - but there's also
the Framework Laptop which you can actually buy (er, subject to availability...). That looks rather nice - except the I/O is a bit limited (only 4 ports and no Thunderbolt/USB4).
There's also Apple's new
Self-Repair Program which is supposedly rolling out to Macs real soon now.
These things all depend on the price and availability of parts and tools, of course. Laptops are never going to be like PC Desktops with truly interchangeable components from multiple sources - especially if people don't want them as thick as a brick... although standard SSD blades (as in the framework and some other laptops) are a start.
In the case of RAM, the limitation is that LPDDR RAM is
only available in surface-mount chip form - there's no equivalent of the standard plug-in DIMM - for good reasons, because the data lines to the CPU need to be kept as short as possible to achieve high speed at low power. With the M1, having the RAM integrated in the SoC package gives a performance advantage. In the case of RAM, Apple's problem is the ridiculous prices they charge for BTO RAM upgrades, encouraging people to cut corners: it's 2021 and having 16 (consumer) or 32 (pro) GB of RAM on a premium laptop shouldn't be an expensive luxury.
Soldered-in SSDs are harder to defend (unless you're talking about mobile/tablet devices) -
maybe they get some speed/power advantage from surface mounting, but the the read/write speed of the medium itself is still an order of magnitude slower than RAM so that's not obvious. Also, SSD still
has a limited number of write cycles - so not making it replaceable is just potty (let alone using 'because security' as an excuse for making it non-replaceable). OK, the expected lifetime of SSD "under normal conditions" may compare favourably with the MTBF of mechanical HDs, but, then, mechanical HDs are typical replaceable... and it's quite conceivable for a software bug or malware (or excessive swapping because Apple made you nickel-and-dime yourself on RAM) to cause an abnormal level of SSD writes...