Ah, okay. So you just mean underground buildings and caves with unique names, and not dungeon raids.
I don't see why they wouldn't include such areas. 1.0 had quite a few underground places (I'm thinking of the mines in Thanolan) and unless Yoshi has had Bahamut collapse those mines into Instanced Dungeon Onry, they'll still be there in one form or another.
Yup basically something like Garlaige Citadel (minus those stupid banishing gate switches).. I love to feel of exploring a new dungeon solo and happening across another player exploring too and we happen to team up (or I find him dead while exploring and I raise him) or knowing that while Im exploring this dungeon incase I start getting my butt kicked I can do so knowing that "any second" someone might appear out of nowhere and start throwing Heals my way (or Raise me if Im laying there dead when they do show up).
Or that time when youre on a mission as a newbie.. going to said area seeing its a BCNM like boss battle... you go in solo thinking you can beat it.. get pwned and get tossed out... you notice some other newbie show up with the same idea you had... you warn him or her. the two of you then decide to team up and you take the boss down.
Those are the kinda experiences that form a community/bonds/friendships, things youll never get from just Queuing for an instance and getting tossed in with a bunch of randoms. So Im hoping there will be some or even just ONE experience like that to look forward to.