"It makes sense for HP to target the enterprise audience with its premium smartphone, especially with Windows Phone so unpopular among consumers. "
I think it's a great news for Microsoft and a positive change to see. Earlier on when Microsoft acquired Nokia, they limited the Windows OS to only Nokia devices and wanted to be the exclusive Windows Phone manufacturer. This resulted in an overall limitation in the number of Windows Phone users and Microsoft lost sales. If other manufacturers come up with Windows devices, it'll increase the user base and eventually bring in more developers to develop apps for Windows. This will result in the increase in sales for Microsoft's own devices as well.