If we as people ever manage to convince em to indeed release a 3rd and final expansion,since 3 is always the magical number. I believe they can release it pretty quickly. They already worked on Iorveth and his Elves years prior and cut him off only 1 year before release so I doubt it's gonna take em a while to make up content. Here's a bit of information I found on a post in reddit about cut off Content on Iorveth/Scoia'tel.
Also here's some stuff about Iorveth's development
Iorveth's role was quite important to the original script from 2014. He was a main character
He was cut from the game somewhere around Feb 2014, along with a bunch of other content. He would have appeared in at least 6 quests (Pyres of Novigrad. Get Junior, a deleted large Novigrad side-quest titled sq305-Scoia'tael, another cut one called sq309-Investigation, The Battle of
Spoiler, and Final Preparations). Geralt would find him in Novigrad.
sq309-Investigation would have involved him hiding in a basement of a house in the non-human district, playing his flute (using the same song - Stella Splendens - from his intro in TW2). The in-progress asset list was very particular about that song, that quest would have also featured an Elven Portal, it's not specified what it would be used for.
A part of the cut Scoia'tael side quest would have involved Isengrim and two other Scoia'tael commanders. The only one that actually made it into the game was Vernossiel, the commander in the Woodland Beast quest. I doubt that was her original role, as Woodland Beast isn't mentioned in the 2014 files.
He would helped Geralt find Triss too. They would go to her house together. This makes a lot of sense depending on your choices in TW2, as Triss can save his life in the epilogue. No doubt that he would have felt that he owed her one. He would also have had connections with the criminal underground, knowing both The King of Beggars and Cleaver. They would also have been dialogue scenes with Roche, Iorveth and Geralt at the docks. A bug report from the Alpha states that the writers needed to further explain the relationship dynamic between them, and why they wanted to kill each other.
(spotkanie z Iorwethem - musimy jasno okreslic relacje Roche-Iorweth, chca sie zabic? jakie sa miedzy niemi relacja?)
He was also listed in the in progress Prima Guide.
CDPR also said that he would be in the game.
Everyone will appear in a little bit of different situation than in TW2. For example, time's are changing, and there is no Scoia'tael like there was before. Iorveth is also not the man he was before.
The file names for the dialogue scenes between Letho, Roche and Ves in-game are actually still called 'content8/quests/part_2/quest_files/q403_battle/scenes/q403_10_letho_vs_roche_iorweth.w2scene'. Iorweth is the Polish name for Iorveth.
CDPR never changed the file names because logically, they thought no one would ever see them. Ves was actually only added in late 2014, replacing Iorveth in two KM scenes. It's my speculation that he would have
Spoiler
All of this is also why there's a Scoia'tael Gwent deck in-game, when the Scoia'tael themselves don't actually appear. They were meant to at one point, and the Gwent art was completed quite early into development. Unfortunately, the REDs refuse to comment to me on why they were cut so late.