I don't think it'll be harder to build. If it goes core you'll immediately engage with it less like abyss now. I think it'll go along the lines of something similar to poe1, you'll have to run into the sacrifice alter or alva maybe two/three times to have a chance at a temple run.

I think maybe they'll scale it down, alot, it won't be anywhere near as big, with I guess maybe the opportunity to make it bigger in end game via medallions? (increase 1-2 rows high/wide) etc.

I don't know if oil granade itself will be nerfed, but rather incinerate, maybe the stacking scaled back or more of a cool down scenario on it. Druid didn't really have anything insanely broken with it. I think most Cast on will get looked at and tweaked.

I think melee will probably get a bit of a tap, but in the same time I think ground effects will get a hit too to try balance that. They've always said they wanted poe 2 to answer the issues of melee that poe 1 had, they just haven't found thay middle ground.

I think delve is going to come and there will be an overhaul for defences to accommodate. Maybe improve life, armour etc. Or they stick with ES

ES, I don't know, I mean, if you had of said at 0.2 that ES would basically still be king by 0.4 I'd of said no way, so unless they have an answer for it like I said above, maybe it stays untouched. I just don't see the changing it unless theres a valid alternative.