I have doubts 4k will ever be more than a premium service delivered via streaming video or possibly disc or flash drives, it's hard to get good 1080 via streaming as it is, the IP's aren't going to be happy about the extra bandwidth of 4k.
That said I doubt it'll make standard HD sets obsolete any time soon, or at least not until most of them have been replaced with whatever is the newer standard.
It's all Digital so it shouldn't be too hard to make it compatible either by upscaling or downscaling, same as you can watch videos from 240 to 4k now on your Computer.
I'm happy now with regular "old" 1080P HD but in ten years who knows. As my eyes get older the sets get better so it all kind of evens out.
Maybe I can just get an Implant by then and watch TV inside my head.