What this downloader does is, when the Company releases Windows 10 it will download the base Windows 10 Installer which when installed will further fetch all the necessary files like drivers etcetera and all..
It appears Microsoft is serious when it comes to upgrading Windows 7 and Windows 8.1 users to Windows 10. The upgrade will be free in the first year and it appears Microsoft will take that time to convince users to upgrade. Users that don’t want to receive the upgrade “advertisements” should simply not install the recommend update. If Microsoft however decides to make KB3035583 an important update it will install automatically with other Windows update.