This is already happening...at least in the university my kids went to.  Each course they took was also available online.

According to my kids, the difference between the sessional instructors (who are not grad students, but professional practitioners with decades of experience and with Masters or PhD degrees) and the full-time PhD's was even more pronounced with online courses.  That's because the full-time PhD's often "mail it in" (i.e. least effort possible), while the sessional instructors may teach only one or two courses a term and give it their all.  Online courses are not simply "self-study"; the need for online facilitation is very important and requires truly engaged profs to provide the best learning experience.

The kids know this.  They use Ratemyprofessors.com to find the most engaging teachers and avoid the duds as much as possible.