I think that schools will be completely replaced, not by online schooling but by the eventual economic and governmental collapse.
Whether the replacement will involve online learning depends on whether the internet survives that collapse in a reasonable working order.
Assuming it does, locally controlled schools will use online learning for reasons of economy and efficiency. This will be especially true at the secondary and post-secondary level if there is a labor shortage due to a booming recovery economy or a large population reduction from violence suffered during the collapse.
Minimum wage and teens with nothing to do will be a memory, as will public employee unions.
I presume that in your prediction, in the economic recovery phase there will be so much work to do and such a dire need for everyone to be productive that the idea of anyone not being able to find a job will be a complete non-issue. Not only will there be some sort of job for every single able bodied American who can work but the society will leave its current entitlement phase entirely and demand that every American, who is capable of working, goes out and gets the jobs that they will be most productive in. Is that a correct assessment of what you are saying?