From the stream yesterday (14th September 2018):

CrateEntertainment can you tell us more about the release date?

Yeah, that question's been coming up over and over and what I'm going to tell you guys is that we're actually going to be pushing the expansion back to quarter one 2019. Probably not the answer people wanted to hear to that question. There are a couple of reasons for that: We want more time to keep our Crate Entertainment quality bar high. The expansion has gotten really big as is our standard, as you can imagine. So once again a big expansion with way too much stuff, and just as we went through things in internal testing we weren't really fully happy with them as they were and given that we have that option to extend the deadline - we're not bound to publisher due dates here - so we thought why stick to what we think is okay, when we know we can do better. So we're actually revising some of the areas we built, we've had some animations that needed revising so yes, sorry, going to come out quarter one 2019, not 2018. Official. It's not coming this year.

http://grimdawn.com/forums/showthread.php?t=77182

It could even be a good april fool surprise.

Well could go either way Eriss. It would either be that everyone wouldn't believe it if they released it on that date - given the hilarious April Fool's Day GM's they've done before - or it would be the best April Fool's Day surprise EVER!

Still, I don't think/hope it'll take that long. I think it's more likely a combo of, as they said, there are some things they're not happy with plus the fact that the new Shattered Realm game mode is still being added to/improved with the playtesters input. Zantai said in the stream they've already changed it 3 times and testing is still ongoing. While I'm sure they allowed for such feedback to make alterations, there may have been more than they originally allowed for time-wise which may have added to the pressure to meet their original target date.

I'd prefer them to patch it first, and then release it after it's ready, rather than the more common way of "release now, patch later" that other games do, which means we end up with a buggy mess that isn't going to be worth playing until after they've patched it anyway.

Zantai did say there'd be a pre-release patch probably shortly before FG goes live. But there'll still likely be a patch afterwards, just the nature of game development. You never find all the bugs, no matter how much testing you do. Someone on the GD Discord found a Crucible bug yesterday and that's been out for over 2 years now. At least with digital downloads we can have patches that fix things rather than just having to live with them.

Calendar Q1 or Financial Q1?

Calendar - some time between January and March.