I think we need to be little more realistic here... IMHO, 2160p @ 30fps is actually a very realistic target, as long as it keeps it rock steady, I would be pretty satisfied.
For a lot of developers - visual fidelity is probably more important than framerates - because one directly affects sales, yet the other can't be really shown unless you play the game. A lot of them chosen the visual fidelity over frame rates. It really comes down to the choice of the developers, and if they tout locked 60fps or 120fps even and it looked like last gen game... it wont' appeal to the users well.
Of course I would love to see every game locked at 2160p @ 60fps - but all games push the hardware in different manner and all have different art style and skill level of doing so. I think 1440p @ 60fps or 2160p @ 30fps would be more common resolution. Then again, this time CPU has so much power, I could be very much wrong about it - and I am hopeful for 4k 60fps would be achievable with incredible visual effects all turned on, as developers get to know the system better and better, and find out more ways to churn out more fps without sacrificing the screen effects and polygons.