I think windows will continue to dominate the business desktop space. There’s just so much legacy software to support that makes any transition difficult. Consumer desktop users could end up switching to laptops which does create an opportunity for macOS more than Linux
Unlikely. There is just too large an installed base of software that will only run on Windows and is widely in use.
However, we have to acknowledge that if you consider Android as being Linux based and all the servers in the cloud, then Linux has already supplanted Windows.