Even if they eliminate the price difference between a 5G vs non-5G capable laptop - maybe integrating 5G modems into standard WiFi chipsets - I still don't see it being a generally desirable trait, as now you have to maintain or even pay for another account to use it with, rather than using my already existing account on my phone.
My office-issued laptop has an LTE modem. It is quite nice, especially since it can use a much better antenna than my cell phone, and hence can get decent signal even when my phone has to fall back to 2G. However, it hardly ever gets used anymore. In addition to the issues you mention, there are also drivers. They have been quite wobbly under Windows 10, and a complete crapshoot with NetworkManager/ModemManager: the underlying kernel driver will work fine, but the ModemManager (god, I hate capitalized utility names!) won't talk to it unless I hunt down a very specific point version, and rebuild it myself - at which point the system's NetworkManager won't talk to the ModemManager, and would need to be rebuilt as well. Since my primary work environment is under Linux, I just eventually gave up. That was a couple of years ago; may be the things have improved since then, but I no longer care enough to try again - tethering to a cell phone simply works, and is completely hassle-free.