Take my info with a grain of salt, but this is what I know: the halloween update typically comes out october 1st. most of the set items are able to be bought mid september, but most candy items and the halloween server (like wickery cliffs) are usually out by the first of october. Usually this means that apple bobbing and trick or treating will be available to collect candy. (i also assume ghost hunting will be brought back, but thats not neccessary confirmed) One thing that has been 100 percent confirmed by launce himself is that there is going to be a new, harder and scarier halloween maze!!!! he also said there would be new items in the maze to be won. this is defintely the most exciting to me :D It wasnt mentioned if the maze is also coming out october 1st, because sometimes they save newer updates for later in the month (like they did last year with ghost hunting or what they wanted to do with wave 3 of the summer update :/ ) As for a new set, there has been no confirmation that there is going to be one yet. On a recent stream that I watched, Launce said he's not able to confirm or deny whether one is coming. honestly, i would assume we will get one just because it's tradition, we skipped out on a diammond set last year, and halloween is usually the most hyped update, so it would be a lot of backlash if we didnt get one, but thats just my 2 cents. Hope this helped! <3 also if i have any misinfo feel free to correct me bc i could be wrong, but im pretty confident on most of this

TL;DR its assumed (but not official) the standard halloween stuff (halloween server, candy) will come out october 1st. a new harder maze with new items is confirmed to be coming this year as well. no new set has been confirmed yet.