It's probably a transition. Apple doubled down on engineering and integration feats due the the mobile ecosystem and marketing lever (mind you MS is taking that road too if you look at Surface tech talks and ads). So things were standardless (non-disk-form-factor SSD), some things were soldered. Unless it never profitable again to have pluggable boards (let's say if simpler to just tape a new SoC and access cloud data) it will come back. Modular cell phones projects exist, tiny usb3 sockets that can be used for almost any device, etc etc I'd bet we will have gumstix like modules in laptops. Might also help durability since you don't have to avoid breaking a big motherboard full of surface mounted components.