It is very obvious to assume that Rock Smash will remain a TM. The reason why I say this is because they cannot put it as a TM like it was before in Gold and Silver because in DPPt a Rock Smash TM was never formed, but instead it was placed as a HM like in RSE and FRLG. So, thinking Rock Smash may come as a TM probably won't happen, that I can tell.
Also, it is safe to assume that Flash won't be brought back as an HM either, because in DPPt it was placed as a TM. So, because of compatability and no doubt they shall allow trade with TMs being held, Flash shall more than likely remain as a TM for the remakes. However, this does leave two empty places for HMs that will need to take use once more. So, my though for this is, Defog will be kept as an HM for the remakes to replace the areas where the caves were placed as dark. Actually, even the dark caves before can be kept without fog, such as Dark Cave, so it can stay true to its name. However, other areas can be replaced with fog over darkness like before.
Then, there is Rock Climb, which I too doubt won't be brought in as an HM. So, with this being said it can easily be replaced with the original Whirlpool HM from Gold and Silver. This wouldn't cause much problem at all because of how HMs cannot be traded or held as an item. The only thing I see here is that there will be three water type HMs [Surf, Waterfall, and Whirlpool]. So, by thinking this, it makes me wonder whether or not Whirlpool will become an HM or not, because I'm sure Waterfall will be kept as an HM like it was since RSE.
My set up for this though for the HMs might be like this [not in order]
- Cut
- Surf
- Rock Smash
- Strength
- Defog
- Whirlpool/Waterfall
- Fly
- Whirlpool/Waterfall
Hmm, it seems as though I cannot think of anything else for the eight slot other than it being another water type HM. However, this could actually make a bit of sense seeing as they've added extra water areas within the game unlike before. So, we'll see.