I also would be interested to understand what part of Kotlin/Native, Konan etc. will be open source and what part will require closed source or commercial feature. Behind this question I would like to understand if Kotlin/Native will be a viable platform to develop Open Source native frontend/backend libraries and applications.

compiler and runtime will always be open source, the only closed-sourced part is around IDE

OK thanks, I guess it will allow less sophisticated open source IDE support from the community if Kotlin/Native gain some traction via Code/Sublime test plugins

Greater tooling support will heavily depend on having a stable Kotlin compiler API that tool devs can use.