Does it cost universities less to teach online? As more colleges stay online, students demand tuition cuts
The article talks about students demanding tuition cuts because online classes are less effective, and because lots of things they pay for are no longer relevant (such as campus transport). It notably doesn't say if it is actually cheaper for the university to teach online. If it isn't cheaper, then if the university cuts tuition fees it would have to make up the shortfall from somewhere.
Is it cheaper for universities to teach online than in-person?
Consider the University of California system as an example: of its core funds expenditures, three quarters goes to employees, and most of the rest is student financial aid. Only 6% of the costs go to equipment, utilities, and similar.
Now, some portion of those employees would also become unnecessary if they did away with a physical campus entirely, but most are still needed to operate the organization. In the case of an institution like the UC system, remember also that much of the physical campus is also not devoted to instruction, but to research and other non-instructional activities, and these have continued in many cases (albeit with reduced capacity) through the pandemic.
In short: in the near term, most universities' costs are almost entirely identical while teaching online.  In the long term, even if they shed every physical aspect of instruction, the costs would not go down all that much unless the institution was radically restructured to greatly increase the numbers of students per instructor.