This comment seems to misunderstand professors and universities. Instruction is a relatively small part of professor responsibilities. Most tenured professors will teach perhaps one class a year, some one class a semester. Some do more, though often by choice and at least at Georgia Tech, much of the undergraduate instruction is done by lecturers, who are not tenure track faculty.
So the value they produce won't decrease by much. In fact it might actually increase. Georgia Tech is, and has been, one of the leaders in online instruction through the OMSCS program. This allowed professors to be in many ways more valuable and teach more students per professor (with an increase in TAs).
My experience is limited mostly to the College of Computing, but some courses taught by other Colleges (notably gen-ed physics I and II in the College of Sciences) have been optionally taught in mixed online form for years (I took an "inverted" Physics course where the lectures were online in 2014). This allowed in-lecture time to be much more tailored to specific student questions.
So there's no a priori reason to believe that online instruction is less valuable. (This isn't the same, by the way, as the opinion that university education that is completely online is as valuable as in person, there are environmental factors that are advantageous for in person experiences).
There are some classes and subjects where this doesn't always work (Engineering courses often need specialized equipment for more applied course), but these aren't the majority of classes, and forcing a CS professor to lecture in person when the same course, often taught by the same professor, already exists as a MOOC is ridiculous.