Why don't they fill us in on that then?
As I do not work for TFP, TT, or IG, beats the hell out of me. However, I could make a few suppositions if you'd like. Which you will find below if you are interested. Fair warning though, some of my reasoning might seem insulting to the developers. That's not the intent however, they are included for the sake of speculation not as fact or accusation.
REASONS DEVELOPERS CAN'T OR WON'T FILL US IN
1. They aren't sure themselves.
As far as I know(and I could be wrong) Unity is still a relatively new game engine platform for consoles, so it's entirely possible the developers themselves aren't exactly sure what they will and/or will not be able to do/add even with the updated engine. Given the limitations of the consoles as being barely above basic spec requirements this seems like a viable reason. Granted they could just come out and say as much, but that's another topic entirely. The point is, they might not be sure themselves beyond what it allows for bug fixes and don't want to get peoples hopes to high. Personally, I think this is the most likely reason. Which is why I started with it.
2. They are just incompetent.
Maybe the developers are incompetent at game design or porting the game, or both. I'm not sure I'd buy this one considering how many new survival genre games have been popping up. The genre was rare and extremely poorly done before 7 Days to Die came to consoles. Arguably showing other developers there is a market for the genre. Though, none of them have created an entirely destructive environment like 7 Days to Die has with its voxel style as far as I know. Which speaks volumes about their competence, both the original developers and the team responsible for the console port. So seems highly unlikely to be a viable reason.
3. They are just donkeyholes.
It's possible, though unlikely in my opinion, that the developers just don't care and are major donkeyholes. This argument is made often, and repeatedly, by many people. Including yourself, Kilgore. Personally, I have my doubts for this one based on the efforts and time put in trying to improve the console experience. As I've stated before on these forums, given the fact that the console version was released as a finished product based on the Alpha 14 version of the PC game the developers are under no obligation to inlude more content. They could have just stuck with fixing the bugs that could be fixed and left it at that. They didn't, choosing instead to add new content, optimization, even updating the engine as we see coming sooner or later. That alone leads me to believe this possible reason is highly unlikely. I could be wrong, I admit, but I seriously doubt it based on the evidence I have seen.
Anyway, there are my three primary reasons why the developers might not be sharing the exact details of what an updated engine will bring. As I state above, I personally think the reason is number 1. They just aren't sure themselves what can and can't be added. Given the things I know thus far, such as console limitations, that seems the most viable explanation to me.