Dragon Age 2 wasn't Frostbite 3. You're talking about little league and major league here, EA & DICE are not into all that.
The main evolution from Eclipse/Lycium to Frostbite is graphical. The main thing Frostbite is updating is the graphics, animation, and physics, to make it all more realistic.
Personally, I suspect the things some people want to "touch" or edit in DAI are still in 2DA files (essentially 2 dimensional arrays like an Excel spreadsheet), like how many points you get when you level, or the experience points you get for certain things. For the record, Bioware used 2DA files in BG2, in NWN1, DA1 & 2, and I feel safe betting they'll continue to use them in DAI.
Oh, I could be wrong, but I am calling this as a safe bet.
(For the record, Bioware documents the filetype here:)
http://social.biowar...t/index.php/2DA
Everybody talks about the difficulty modding Battlefield 4. But here's the deal. That game was heavily focused on multiplayer matches. It was practically the main focus of it, though there was a SP campaign. For obvious reasons, when MP is the focus of your game, you'll do what you can to discourage mod use. So yes, they definitely took a position of "no official support". DAI may have MP (we still don't know) but I think we can all agree given how little they've discussed it to date, it will NOT be the focus of the game. I do not believe the Frostbite engine was built to defeat modding, but BF4, built around the engine, was coded as a whole to discourage it. There's a difference.
DAI does not have the incentive to disincentivize mods the way that Battlefield 4 did.
But for those who say you can't do it in BF4 -- get schooled. This guy did it.
http://www.thetechga...p=32388753.html
It can be done. It may take hex editing, and patience, and your eyes may have glazed over his description, but it can be done. Homey even seems to have changed his field of view on his Xbox!
Because this is a new graphics engine, the way things are graphically represented in files will change the most. Thus, much as I hate to say it, the things that might be hardest to do are new texture or appearance mods.
Also, it should be noted that there are generally less mods for shooters like BF4 than CRPGs in general ... why? Because there are less things people are interested in changing. So there might be fewer mods because there are fewer things people want to change.
Everybody talks about the texture pack mod for BF4 which took a year to do. Well, like I keep saying, new graphic engine = new ways of representing texture data in graphical files = new challenges.
Honestly, doing basic gameplay mods, like changing how many attribute points you get per level, will still be pretty easy. 