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
Offline use of win32 aps is awesome, but launching over internet is also, imagine you can get top performance in small package - because heavy computing is done elsewhere. With good network you can get better battery endurance also launch some demanding apps / games... like playing Halo with ''phone''.