Very likely there will be a 720p/1080p option, probably SD as well. But yeah given iplayer issues this may well be an underfunded venture thats too ambitious, we will see.
Personally I dont care for 4k, I dont feel the need to have something like a 50inch screen, and on a 32inch screen, 4k is barely different to 1080p.
The main reason people see a difference is probably due to higher bitrates rather than increased resolution. e.g. when sky released HD they reduced the bitrates of their SD to make HD more attractive.
Proper innovation is having things like player cam's and split screen replays, but the media companies just seem dumb and think innovation is just adding pixels.