There are no other major WWE or AEW PPVs between now and HIAC, but there is a lot happening in the wrestling business between now and then.
First, starting this coming Wednesday, NXT moves to USA. For the first two weeks the first hour will be aired live on USA with the second hour live on the WWE Network (due to the last two episodes of Suits). After that, NXT in its entirety will be aired on USA with replays available on WWE Network.
Next, starting on October 2, AEW on TNT (the current working title) will debut on, obviously, TNT.
Next, on October 4, SmackDown officially moves to FOX and back to Friday nights. It will also be dropping the "Live" part of the name which nobody liked.
Next, following HIAC, on Friday, October 11 WWE will conduct a draft on SmackDown to realign its rosters. The draft will continue on Monday on Raw.
Finally, this last week Anthem, the owner of Impact Wrestling, bought a majority share of AXS. That means at some point in the near future Impact will be aired on AXS. It is also anticipated that this move is in part to pressure NJPW into a working relationship with Impact (and dropping ROH in the process), or Anthem will drop NJPW's TV deal with AXS. While there is no doubt NJPW would likely love to drop its relationship with ROH at this point, it's likely NJPW has no desire to work with Impact, not after how TNA treated Okada(? - I think that's the guy) when he was loaned to them. Granted, that was a long time ago and the people that made Okada look like an absolute fool on TNA no longer have anything to do with Impact, however, just the fact that Impact is trying to blackball them into working with them isn't a good look.