Will there be an option for 4k?
It is targeting mostly people which have a slow connection but some may also have a good connection too.
I think so but probably not for all the content. YourDef is a good idea. You don't need 4k streams on a phone.
Have a look into the whitepaper. There is the posibility of flexible resolution. For examble a mobile device got a lower quality than a TV on streaming.
of course the will be an option for 4k. by the time the platform is completely operational, it will be mandatory.
If we talk about movies or series, for now HD and Full HD more than enough - although of course in the future it may be in demand and filmmakers can be able to create 4k quality.