Look, the real question for DE to solve is quite simple - can it keep the player engaged with slow-paced, passive and repetitive gameplay throughout a 50 hour game.
Traditional RPGs have incredibly varied gameplay. You get periods of repetitive problem solving (inventory management, minigames and so on), you have periods of passive reading and inbetween all that, you get periods of fast-paced combat. Scrap all that and you're left with what? Age of Decadence CYOA elements deservedly got a lot of praise, but they were balanced out with brutal combat system. Does anybody want
Vault Dweller to make AoD2-visual novel edition, where all you ever do is juggle skill points to pass skill checks? Thought so.
Numenera went over the top with complicated dialogue mechanics, fancy dice rolls and checks running under the hood, but playing it felt like playing a sudoku with graphics. And I have yet to see one example of what Disco Elysium does differently, other than it has a better premise for a sudoku with graphics.
The reason why a visual-novel edition of AoD would be a terrible idea is because the game is quite lacking in ambition, the gameworld feels very empty, there aren't many characters or dialogue options and there aren't really many ways to solve problems since the game is completely on rails, a specialised character doesn't really have many options at all and a jack of all trades character is just not gonna work, so you just end up with a game where all you have to do is specialise your character and then breeze through it by choosing the few skill checks that fit your build.
DE is different for several reasons:
1- The scale and ambition of the game seem to be much much larger, which means there is a possibility that quests have several solutions for any specific build and that the game is less railroad-y (we'll have to wait and see).
2- The skill checks aren't simple success or failure buttons like in AoD, from what i've seen from the gameplay most skill checks aren't like that, many skill checks are activated automatically, much like a perception check in fallout, that give you hints on how to interrogate a person, or define what kind of first impression you give to people, but you'll still have to do the talking yourself, passing skill checks is more or less there to aid you, not to outright tell you what to say or do (like in AoD), it isn't that type of game where you can just specialise in a skill like persuation and ace every conversation all your way to the end.
3- The open ended aspect of the game indicates that it's much less linear then AoD, and i am not saying AoD is linear, it's just that you'll always go through the same events, interact with the same characters and teleport from location to location in the same order in every single run.
4- Appearently certain decisions you make and dialogue options you choose in a conversation can influence the difficulty of passing skill checks later, if you find yourself having to extract informations from someone you insulted just seconds before, it's gonna be harder to do it even if you have the skills for it, but i don't know how much of these type of situations will be in the game and i am looking forward to it.
None of this means that DE will 100% deliver on its promises of course, we will have to wait and see, and for now i still have alot of reservations about the game, and i have my doubts on whether or not a gamplay that completely depends on text and dialogue will manage to keep me interested for 60 hours or so.