For schools in good financial states (they are few in number), I think they will actually trend in this direction.
The most prestigious medical schools, engineering schools, etc. actually make a ton of money from non-tuition-based sources. Income from patent licensing, federal research grants, etc. dominate income from tuition.
Some of these schools also have endowments that are absurd multipliers of their annual expenditures.
For these schools, where the lack of tuition isn't such a near-term threat, they might actually realize that they can make more money in the long-term (and incentivize better education) by making tuition something more like an ISA.
You've seen it already, where some schools are offering "free tuition", because the value of the labor they get from their students is already greater than the tuition they charge. There's also probably some good tax benefits to writing off the expense of education, in these scenarios. https://med.nyu.edu/education/md-degree/md-affordability-fin...
Especially when you include the tax benefits, free tuition might actually be cheaper than an ISA, because enforcing an ISA requires operational overhead.