Man, I don't know how you can fail to find anything to get on the One this year. Here's the list of stuff I'm considering:
Dragon Ball Xenoverse
Screamride
Battlefield: Hardline (depending heavily on how I feel about the beta; never gotten a BF title before)
The Witcher 3 (but only if I can get the first two games on Steam and play through them)
The Elder Scrolls Online (because they're dropping the sub)
Halo 5: Guardians
Crackdown
The Division
DOOM
Forza Motorsport 6 (if I stop being mad at Turn 10 by the time it comes out)
Kingdom Hearts III (though I'm unconvinced that it's coming out this year)
PGA Tour Golf (depending on how it's received)
Quantum Break
Rainbow Six: Siege
Scalebound
There's a crapload of stuff I'm considering getting this year. Halo and The Division are the only must-buys, but there's SO MUCH that could be out there to play that I don't know how you can manage to find nothing exciting.
Year 2014 was very good for me, while many complained that it sucked, I guess it's preferences
Out of the ones you listed, I'm interested in Witcher, Division, TES: Online and Halo 5. However they are all with certain conditions. Witcher isn't really one of my "primary genres". I will most likely get it at some point, but as said it's likely gonna be something I pick up when I find it cheap just to play it through. Not having played Witcher's before is also kind of a letdown for me like you kinda mentioned too. Division looks really interesting, but as said I refuse to be hyped or even really wait for it until we get something alot more substantial about the game. I tried TES: Online in PC beta, my first thoughts were that it seemed to be designed more with consoles in mind. With the sub dropping I'm also pretty interested in that, but only really if at least one of my friends also gets it, preferably 2. Halo 5 is also a "pick it up second hand/cheap to go through campaign"-kinda deal. I'm currently going through Halo MCC mostly to "sophisticate myself", I play a lot of shooters but the mechanics of Halo kinda make me go meh, but the franchise is too legendary to pass up, especially with such a great deal as Halo MCC existing.
I tried Hardline's PC beta. It was... not too bad, but it kinda felt like reskinned BF4, which isn't necessarily a bad thing. BF4's flawed launch put aside, it's a pretty solid game when it works. Hardline makes the emphasis more fresh and interesting (not soldiers and war like every game in the genre, but the cops and robbers and the new weaponry due to that theme) setting. However overall the beta just didn't really leave me longing for more personally. Will probably give it a whirl on Xbox One too, it's a long time since PC beta anyways.
So I'm definitely buying several titles (even if not all 2015 titles) for the One also this year. It's just that not one of those games make me go "I have to have this", the feeling I had
several times during 2014.
EDIT: I am kinda looking forwards two new F2P titles on Xbox One though. APB Reloaded and SMITE. APB should be out this year, but I don't think SMITE's schedule is known at this time, I'd assume during 2015 though.