But schools nevertheless are threatened by that kind of thinking because it carries the consequence of lost funding, which could be potentially devastating at a time when their costs are almost certain to rise and state budget shortfalls may translate into cuts to per-pupil funding amounts.
I'm a public school teacher, and also a big advocate of school choice. And unlike some politicians, when I say "school choice", I mean a choice that parents pay for themselves. If you want private school, fine. Finance it yourself and send your child there. If you want to homeschool, then carve out the time to do so and homeschool your child for as long as you're able. None of that threatens me. In fact, I've done each option myself, as I very briefly homeschooled my son when he had some special needs when younger & public school just wasn't working for him that year. As a working mom I could not do that for long, and since then I have had him in private schools. They have been great for him. Public school was great for him, too, in Kinder and first grades, but second and third were a nightmare, so finally I took him out.
My point is that kids enter and leave schools all the time, and in general, that is not a threat to public schools. Charter schools have hurt the lower performing, lower income schools in one district in my city, but that is because it took large numbers of kids out due to long term, pervasive social and educational problems at those schools. Those are not communities where homeschooling is common. Covid isnt going to make the exodus from those schools any worse than it already is.
The families who turn to homeschooling tend to be middle class, with access to fair to excellent schools depending on the local district. I've known many, as for several years I taught at a diverse charter school and we got a fair number of kids who "aged out of" homeschool as they reached the middle school years & mom couldn't really teach them everything they needed to know at home anymore. In my experience, parents who are willing to dedicate themselves to homeschooling long term tend to do so due to their ideology: either very conservative religious, or else in pusuit of a more relaxed, individualist type of schooling than is offered in a public school setting. There are non-ideological parents like me, who have homeschooled due to a child's disability, but again, that's a small number of parents and that doesn't hurt public schools. When a child is that hard to teach, it's actually easier on the school (even financially, as less support staff will be required) if parents decide to remove the child.
My bottom line is that it is a lot of work to homeschool long term, and there are multiple reasons why most parents are not inclined to do so. Parents vent, and a small minority might homeschool for a year during this Covid fiasco, but not enough to threaten the public schools in any way.
What genuinely will threaten and damage public schools as a result of closures, are the state budget shortfalls on the horizon, due to dramatically reduced sales tax and income tax revenue. That is a huge problem, and every school district is quietly worried about it.