could they? yes...
Should they? No.
Yes for the bulk of students studying essay/humanities type courses its pretty easy to switch to online learning, and they really won't loose out too much at all from it.
But for any students who need specialist equipment or facilities, its not a good idea, and they would be better deferring the entire year rather than trying to force students online. think about engineering/design students who can't access the machinary to produce things.. music students who can't get to the studios or play together.. science students who cant get to the lab.. film students who can't get to the film gear or organize a shoot.. etc. For courses like that, it would be better to defer it all rather than waste 1/3 of the students courses on severly substandard education.
The only exception may be for first years. In my experiance even in practical courses, first years tend to require the specialist equipment less at first. They aren't doing big projects yet, and they have a lot of learning to do initially first.. so maybe first years could keep going. But if your a 3rd year student who should be doing a massive big practical project, and now its online? Nah... defer. wait until you can actually get your moneys worth.