No, these new dungeon's will not replace the deep dungeon planned for 6.3. This is a completely new type of content for Final Fantasy XIV. For casual and hardcore players alike!
Lets start start this out with the newly announced Variant Dungeon's. According to director and producer Naoki Yoshida, these will be dungeon's with branching paths and a branching story that'll unfold while you go through it.
During your adventures through these dungeon's, a rather wordy NPC from the main scenario quest will accompany the party through the content. The content is also meant to be replayed over and over. So players can experience all the stories that can unfold within the dungeon.
The first one, because Yoshida already confirmed that we'll be getting more through the 6.X patch cycle, will be set in the Sil'dihn Subterrane. Some more attentive players might remember this location from the end of A Realm Reborn. As we made our escape through its aqueducts after the assassination attempt on the sultana of Ul'dah.
Sil'dihn itself has quite the fascinating history. Long ago it existed as a sister state to Ul'dah. And what was at first a shared heritage, would later start what we now know as ‘The War of the Sisters'. As neighbours and rivals do. It is commonly believed that Sil'dihn raised itself to the ground, after it tried to revive its fallen in an effort to wage war with Ul'dah. But those zombies turned on their masters and raised the city to the ground. At least that's how the story goes.
In truth, the Traders' Spurn a powder that'll turn the living into the undead was developed in Ul'dah. And the army of Ul'dah catapulted large amounts of it over the cities walls. Turning the once great city of Sil'dihn against itself. Now over 600 years later, that truth has been almost erased. So we can only wonder what other dark secrets we'll uncover in the ruins of Sil'dihn. Or maybe we'll just get to hang out with the zombies from the A Ream Reborn Hildibrand questline again.
But back to the actual content! In this version of the Variant Dungeon, up to 4 players can enter. You can chose to go in with a premade party, be matched with other players or go in solo. Difficulty will be adjusted depending on party size.
During a run, players can freely change between combat jobs and there are no restrictions on roles either. So if you want to run a DPS only party, or heal each other through the content you can! The only limitation here is that those jobs have to be at level 90 to be able to clear the content.
And the actions of players, will affect the progression through the dungeons. What that means is still up in the air. But we assume that it's not just depending on how fast you slay groups of enemies. There'll probably be some riddles to solve or different paths to take. But the team will probably show off the content in greater detail in the next live letter.
This is only the first of many planned variant dungeon's and it's not like the A Realm Reborn zones are lacking in places that are still left to explore either. Be it the floating city of Nym hovering above Outer La Noscea or the ruins of Gelmorra hidden underneath the Black Shroud. And it's not like there aren't anymore Allagan horrors to uncover either.
The simplest way to describe the Criterion Dungeons is probably that they are the hard and savage versions of the Variant Dungeons. Yoshida has already confirmed that they'll be visually very similarly to the Variant Dungeon but besides that. Both versions will be completely unique to those and their counter part.
There won't be an NPC following you around and there won't be any branching paths either. So this will end up being a very fine tuned experience for those who want to test their mettle in combat. For this players must be in a light party composed of 4 players. With one tank, one healer and two DPS. And while the normal version can be entered similarly to the duty finder. You'll need a premade party for the savage version.
But where does the difficulty come from, you might ask. Well, first of all you won't be able to revive other players with the usual methods. So no raise spells or phoenix downs. Instead every player will get a limited amount of revival actions. In the savage version, player won't be able to revive themselves and the instance will reset, should the party wipe. And there is more! If party doesn't manage to clear out the entire dungeon within a certain timeframe, enemies will become much stronger. So in savage, you are encouraged to reset until you get that perfect run.
Currently we have no idea what the combat encounters in this content will look like. But as always we can make some educated guesses. No doubt that there'll be bosses to fight, this content will probably focus more around having to deal with groups of enemies. A lot of classes have some very decent crowd control abilities, that rarely see use outside of solo content. So we can assume that they'll see more use in here.
There'll probably be a lot more focus on tanking and healing as well. Be it dispelling debuffs or putting some effort into how to place enemies while taking. Maybe having them hit each other with certain abilities or what not. The options are limitless here!
And I would guess the content will also take some inspiration from the Baldesion Arsenal, Delubrum Reginae and especially its savage version. Where players had costume, special abilities that could spiral into some nasty combinations. Just all of that in a smaller scale of only four players. So you can perfectly coordinate your skills and abilities. So don't expect the savage version to be a pushover either.
As for rewards, who knows? There'll be the usual, tomestones and probably some currency for minor rewards like materia and so on. But I'll assume with the relict weapon being more quest based this time around. The Criterion Dungeons will offer an alternate way to obtain gear. If that gear will help you to catch up with savage raids, or just a fun way to gear up alternative jobs is still up in the air. But it's the best guess I have. Unless we'll actually get a follow up to Eureka and Bozja, but it has been awfully quiet around that so I wouldn't bet on it.