Personally, I would like Bethesda to save Hammerfell for a new TES game so we can see it properly with proper quests and lore.
I agree with this. Save Hammerfell for a full game set there. Dwemer ruins, Alik'r warriors, sand dunes.. And then hopefully have somewhere like Thras and Yokuda as expansions.
I'd rather High Rock, the new Orsinium (not included as Hammerfell) or Atmora as place for an expansion for Skyrim as they are better suited and have a lot less chance of being a likely candidate for a future game setting in the series. High Roch has little chance as it'll be too much like Skyrim and people would want something different.