Sad to see them go. There will probably be quite a lot of users interested in Defold.
You’re confusing Corona Labs (enterprise) with Corona SDK.
Corona Labs is closing. But they will release Corona SDK source code with MIT license and it will be possible to perform offline builds.
Also, some community members are trying to raise funds to keep current maintainers of SDK.
That said, for sure many will look for alternatives for Corona. I recommended to some of them gideros mobile, defold and cocos creator.