Sometimes, when one starts approaching government entities to try to participate in big projects, proposed numbers of users can be overwhelming (not billions, but maybe one or two million).
I do realize that these numbers are usually quite overrated, however, as a (hopefully) future service provider, one has to arrive with feasible solutions and approximate costs.
After having read some of the documentation and several threads in different forums, it seems clear that Moodle itself doesn't have any limitations, but that everything resides in the kind of hardware used.
Yes, as it has often been said, one just needs to throw hardware ($) at the problem, but here is where the daunting task arises. For example, based on different total/concurrent user combinations, and maybe rough estimates on the kind of resources to be used (like video, SCORM, quiz), maybe it would be interesting to know the "best" (I know there is no such thing like that) empirical estimates about the hardware configuration one needs to look for in a hosting provider; like a comparative table, maybe?
Though I've mostly been thinking aloud, it sure is a serious issue I'd love to get some feedback on, as we (as an institution) are on the verge of getting into major leagues