The DC will want to be in their classroom, with their teacher. Otherwise I see little point. Aside from the purely childcare point. But I mean in terms of the benefit to the DC.
Surely it makes more sense for the DC to go in maybe one week in, one week off with a thorough clean at the weekend. The survey at my school suggests around a third of parents won't send their DC in so schools may be able to get away with splitting classes in half.
That's without even considering where will all the extra classrooms come from considering the vulnerable and keyworker DC will still be in? And that the teachers of other year groups will still be sending home work and supporting their usual classes.