Even though Polaris will not support Win32 apps natively, Microsoft could use Azure-based remote services like RAIL or VAIL for legacy software. The upcoming Surface Phone is rumored to be the first device that will run Polaris and it is expected to be launched in late 2018.
https://www.notebookcheck.net/Windows-Polaris-could-run-legacy-Win32-apps-through-remote-Azure-servers.281334.0.html