I purchased an SQ-5 last year because I really like the Allen & Heath workflow. I’m slowly adding adds one to it over time. It’s a great console, but it’s missing a few things compared to the WING. I think I’ll add a Waves card soon.
I’d love to upgrade to an Avantis, but I don’t have the kind of clients yet who would justify charging more, so not at this stage unfortunately 
Anyway, what do you think we should expect in a new SQ update ?
Your guess is as good as any. A&H keeps these things very close to the vest, so the odds that there will be any announcement or even a “leak” about such a thing before it actually is released to the public for purchase is pretty low.
Now as far as my personal speculation…
It’s true that the SQ is now the oldest console in the current A&H lineup that hasn’t had a major update/revision yet. The CQ isn’t that old, the QU lineup was recently updated (to match the 96k architecture of the rest of the systems), and both the DLive and Avantis systems have had a major update/upgrade with the RUFX card and 2.0 firmware release.
It also seems that A&H has about a 10 year product lifespan - at least historically - with their digital consoles. Obviously I expect the DLive to run much longer than 10 years with the recent updates, but given the SQ was released in late 2017, one could argue it is due to be replaced within the next few years.
So all that being said, I think the SQ is probably the next console to get an refresh, but I think it will easily be 2-4 years before we see anything released. Again, this is just my personal speculation and I have no information to backup my speculation other than the reasons I just laid out.