The syntax is problematic since it confuses receiver names with normal namespace. The KT-10468 proposal solves this by producing the new syntax and it clearly separates namespace from receivers, also it explicitly shows the number of receivers and their generic parameters.I am not saying that it should be accepted, just that simple dot notation is not good. In my opinion, the feature is very important for language future and should be implemented with utmost care.
I don’t understand how to add comments to proposal, but I want to point out additional problem. We need for nested contexts to be available in function types. Something like (A, B).(C)->D.