What's a module upgrade?
We have Cellular iPads - and have forever - why not an option for a MacBook with it?
I meant, I doubt they'd want to have different versions of the main logic board for Macs. The far lower volumes Mac's sell in makes their logic boards much more expensive than iPhone or iPad logic boards due to economies of scale, and having multiple versions would make them even more expensive.
So by 'module' I meant some kind of add-on component that you could install internally. Common practice back in the day, of course, but not something Apple does anymore. Therefore, if they WERE to do it, which I doubt, it would quite possibly end up as a dongle.
In any event, this was just my guess. Though I think the reasoning is reasonable... haha