Before you all flame me for posting yet-another-when-will-I-get-Android-Q topic (you can flame me, but please read first!) I think there is a possibility that it might happen.
(Granted, very unlikely given how much HMD has shown that it really wants to improve its devices after launch or beyond what it is required to do).
The 8 and 8 Sirocco run the same SoC and the kernel code is the same as far as I know (from XDA people). I know that many other hardware components are different, e.g. camera, display, so it may not be straightforward, but if HMD are already going to develop Android 10/Q for the 8 Sirocco then it should not be a big stretch further to make it available for the 8 either.
Even if HMD don't do it themselves, there is the chance that sufficiently technically minded people can meld the additional bits of the firmware from the 8 into the 10/Q firmware for the Sirocco and make a custom ROM that works and can be kept updated using HMD's OTA updates for the Sirocco.
Like I said, this is speculation, but it's possible although not necessarily probable.
What do you think?