I've asked this in #205, but because it was closed not everyone had the option to see it and answer it.

@xcguang I'd like to ask about what are Espressif plans for NonOS SDK?
Many people are wondering what will happen to it because many awesome projects depend on it, I think about Arduino Core for ESP8266.
There is a discussion started by @devyte about the future of this awesome project.
There is a question asked by @TD-er:

If Espressif is actually putting NonOS to EOL, is there still any reason for them to keep their core libraries closed?

I'd like to ask @igrr @kedars @me-no-dev @projectgus and @Spritetm (because You buys are listed in People section on Github) about Your thoughts about opening those closed libraries.

If NonOS will be discontinued at some point why don't allow other projects (NodeMCU and Arduino Core) to be able to still function without a mass code rewrite.

Projects like Arduino Core and NodeMCU and countless others are the reason why ESP8266 is so popular.
People (at least this was my case) don't choose chip because it looks nice and has feature x, but because there is a great community around it, there are tons of examples and libraries and there are people that spend their free time to make those projects, examples and are dedicated to helping newbies like me.

As @devyte mentioned in this issue one of the option to still maintain Arduino Core is to stick with NonOS and reverse engineer the closed libs. If Espressif would open those libs then that mass effort could be spent on creating new features or fixing bugs instead of recreating parts that already work.