Price vs immersion, even at its current levels the Rift wins hands down to this. You can fly quite happily now using FSX and Flyinside with the Development Kit and racing sims you definitely do not need 4k - although anything upwards of what we have now would be nice.
In order to really have VR become a killer app youll need to be able to read dials properly and spot incoming enemies, probably two generations away. Pending some miracle tech, 4k will be a while after that.
As to controls - being done now using HOTAS and Voiceattack without the need to break immersion. The real problem currently is figuring out a way to manipulate switches and the like in the really complex sims, like the realistic DCS A10C - scrabbling around for a mouse doesnt cut it. You can quite happily fly an F86 without more than a HOTAS and when you get down to the WWII era stuff - no probs.
Anyway, I dont think simmers will define VR. Having a system like this would be nice, but I am not sure it would provide the immersion the Rift gives now, nevermind what it will be like in the short term future.