Oh well It's over,
BUT I asked my tutor this after my trials (she's a HSC marker) because I didn't write a conclusion for one of my essays. She said that in the HSC most of the time you are not deducted marks for anything unless you write things that are straight up wrong/contradicts your argument, so you can only gain marks from writing a conclusion if it adds some value to your essay but you won't necessarily lose marks for not writing one (basically, the only thing you have to lose is if your conclusion would have elevated your answer).
So say the question was on speeches using this year's q as an example (this is what I took from her saying you can only gain not lose marks so this may or may not be the actual way essays are marked)
If your essay was a 15/20 (at the end of your body paragraphs) and in your conclusion you wrote "In conclusion, Sadat's use of powerful rhetoric does/does not come at the expense of substance while Speech 2 does/does not come at the expense of substance" you will not raise your essay to a 16 or higher. If however your include a discussion in your conclusion "Ultimately, while both speeches use powerful rhetoric to manipulate their audience's perspective on -----, Sadat's use of powerful rhetoric comes at the expense of substance as his speech fails to address -----. ----- on the other hand ----- so on".
So to me at least, it seems that if your essay up till the point where your conclusion would have been warrants you an 18/20, you will not be booted down to a 16 or a 17 simply because you failed to spit out the question once more writing in conclusion before it. You might, however, raise your answer to a 19 or a 20 (Imo unlikely unless your conclusion presents points not raised already or you answer the question in your conclusion while you didn't previously in which case you probably wouldn't be getting an 18), if your conclusion is not a mere regurgitation of the question. I think you won't lose marks, I've heard of people not losing marks for not writing a conclusion. In my trial I ended up with a 19/20 and the comment said "Your discussion shows a very authentic engagement with the question. Discussion seems a bit unbalanced with less focus given to related. A pleasure to read". It's hard to tell given so many people are saying you MUST have one. I disagree. Who knows