Your kid will have many full online degrees on the level of conventional M.S., maybe even PhD, once he's adult. These days you have Georgia Tech's OMSCS/OMSA and Duke's MS in Health Analytics already; I am sure more will come.
I doubt there will be online degrees equivalent to a PhD (or calling itself a PhD). The coursework of a PhD is typically very similar to a master's in the same subject (maybe with a few additional requirements) but is usually just a primer for the real work doing our research. Conducting research is an inherently social exercise and the mentorship that is given during a PhD won't be easily replicable with an online program.
I agree with the general point you're making though.
This is one of the things I think about, the alternative options that may expand in the near future. But it kind of goes against half of what I want for him. You're not really breaking out of your parent's orbit and flying on your own when you sit on a computer at your parent's house. It seems like a good option for people who are past that age, living on their own. But I want him to go out and meet new people, make some mistakes and learn from them.
One program that I got excited about a few years ago (unfortunately I was already an undergrad at the time) was Minerva [0]. It's relatively inexpensive, seems as if the coursework has a lot of rigor, and you get to do a bunch of traveling while in school.
You already have external PhD programs at many universities, just their success rate is usually abysmal, which I believe is often due to non-MOOC basic classes they require. As you mentioned, those are often overlapping with advanced grad courses, so at least that barrier could be gone by time OP's kid is adult.
