The language used in the upgrade details for those that qualify for the Windows 10 Home edition appear to suggest that users on that SKU will not be able to opt out of automatic updates.
All the announcements from Microsoft's Windows 10 Devices event
...of Google's greatest, the wait for Microsoft's latest, and BlackBerry's bad day
Leaked slides confirm Lumia 950 + 950 XL specs, 'Display Dock'
Tesoro Excalibur Spectrum, a colorful Mechanical keyboard review