Windows Phone 8 users won't get Windows 10 until early 2016

Users of older Lumia smartphones with Windows Phone 8 or 8.1 operating systems must continue to wait on Windows 10. Microsoft announced in December that devices will not be equipped with the new software until "early next year," but was not specific about which month of 2016 it had in mind.
As reported by thurrott.com. Windows 10 was originally supposed to be available for the older Windows phones by December 2015.
Microsoft says the new system will be offered on the Lumia phones 430, 435, 532, 535, 540, 635, 640, 640 XL, 735, 830 and 930.
It remains unclear if other older models with only 512 MB of memory will ever get Windows 10 at all, despite an assurance early in 2015 from Microsoft executive Joe Belfiore on Twitter that the company was working on a stripped-down Windows 10 for those cheaper models.
No further information has been provided, so the best advice is: keep listening.