I have that graphics driver(8.15.10.2697 WDDM 1.1). Needed it myself for a dell inspirion. Let me know if you should change your mind about win10. I, too, would like to see you come back.
What 8.1 version you use? If you use an Pro VL and have activated MTK2.x or any other not 100% legit activation, WU may not 'shows' up!
Well what are the chances that we even have to wait for july 29 to get build with activation check, they gotta push some sort of stable build to partners for them to put on devices so it will surely leak, these builds always leak. Unless... they are putting the current and upcoming preview builds on there lewl.
Nobody knows yest what the changes regarding the activation process will be! To find out what that would be, we simply have to wait to see! I don't mind about that, I've available licenses enough which qualifies for the free upgrades, include still unused Windows 7 Licenses beside of the used 8.1 licenses! So, just don't be worry, wait for the final day and see what it will be all about!!