Are there any plans to have kotlinc do incremental compilation on the file level in the near future?
We are woring on the incremental compilation support in the IDE at the moment (won't work in the command line compiler). Hope to get it released rather soon.
Will it work with gradle-based project? When I open it and build it in IDE?
Most probably yes
Do you have an ETA for the feature?
It will be done in a month or two, may be sooner if things go very smoothly.