How they would replace the revenue is mostly irrelevant. If it's unconstitutional, it's unconstitutional and needs to go. Making the government live within it's means, reducing the scope of public education back to education itself, and restoring local funding and oversight to public education would all have to take place as a matter of course. Public education has extended itself so far beyond the "general diffusion of knowledge" required constitutionally that it has even failed at that minimum standard.
