Which smartphones are eligible for official (production-pushed) Windows 10 Mobile updates depends largely on their age. Which is why the Lumia 640 and 640 XL, hanging in there gamely for the Creators Update (CU), have now been dropped from the official list for the Fall Creators Update (FCU). Of course, there's nothing to stop anyone with a Lumia 640/XL diving on the Insiders programme to get the latest Fast or Slow or RP ring builds of FCU and then leaving the programme so as to jump themselves onto the FCU branch for good and get the monthly updates. That's the way readers here should go for any owned 640 devices, I think. Regular users will be fine with CU and won't care, plus - if we're honest - the two branches aren't that different for Windows 10 Mobile for consumers.

Anyway, from the Microsoft post:

The Windows 10 Creators Update (1703) is only available for the following Windows 10 Mobile devices, and availability may vary by carrier and market: HP Elite x3, HP Elite x3 (Verizon), HP Elite x3 (Telstra), Wileyfox Pro, Microsoft Lumia 550, Microsoft Lumia 640/640XL, Microsoft Lumia 650, Microsoft Lumia 950/950 XL, Alcatel IDOL 4S, Alcatel IDOL 4S Pro, Alcatel OneTouch Fierce XL, Softbank 503LV, VAIO Phone Biz, MouseComputer MADOSMA Q501, MouseComputer MADOSMA Q601, Trinity NuAns Neo.

The Windows 10 Fall Creators Update (1709) is only available for the following Windows 10 Mobile devices, and availability may vary by carrier and market: HP Elite x3, HP Elite x3 (Verizon), HP Elite x3 (Telstra), Wileyfox Pro, Microsoft Lumia 550, Microsoft Lumia 650, Microsoft Lumia 950/950 XL, Alcatel IDOL 4S, Alcatel IDOL 4S Pro, Alcatel OneTouch Fierce XL, Softbank 503LV, VAIO Phone Biz, MouseComputer MADOSMA Q601, Trinity NuAns Neo.

Windows 10 Mobile devices not listed above will continue to receive security and servicing updates according to Microsoft’s Support Lifecycle policies.

So nothing really new here, I was surprised that the 640 range got the CU officially, to be honest, so it's time had definitely come. The Wileyfox Pro is mentioned on both lists, despite not having been released yet, so this device must still be very much a 'go' and I'll try again to get a review unit.

The lifecycle policies referred to just mean that each new branch gets supported with updates for two years. Hence my oft-quoted 'Autumn 2019' EOL for this branch - and possible many Windows 10 Mobile phones.