I think users of private schools will need to have a careful think about exactly what they consider their reason for paying for education (and schools, likewise, will need to think about “What are our users’ commonest reasons for paying for education?”)
For each individual (or school), is it mainly about:
a) We want a faster-paced, more challenging academic curriculum than most state schools are able to offer, and peers that are academically above average across the board.
b) Our child has issues with attention space, focus, bullying etc., cannot cope in big state classrooms and needs a small-scale nurturing environment with more personal attention.
c) We want a well-rounded education with marvelous sports and music facilities etc.
d) I and my partner work big busy well paid jobs with long hours; we want good academics, personal attention, extra curric, wraparound care provided as a convenient one-stop shopping trip so we can both focus on our careers.
e) We wouldn’t normally have chosen private, but we’re in a difficult situation where the only state schools available for us are really bad/scary etc.
Some of those motivations offer the potential for increasing class sizes and/or selling off/monetizing some of the facilities without parents refusing to pay for it (for example, it’s possible to deliver a fast-paced curriculum to academically-selected kids in fairly large class sizes), some do not and are very much about seeking a premium product.
No doubt we will see private schools making decisions about what their target markets are, and budgeting accordingly. Or going under in some cases.