Open Sourcing is a lot of work. Plus it might contain (even huge) parts that can not be open sourced. And even unknown parts where real ownership and patents might be unknown.

Where did this bizarre myth start? You apache-license the code you wrote, write a paragraph about code isn't yours or you're not sure about and is therefore missing, and move on with your life.

Patent indemnification is not your problem, it's the problem of whoever wants to use the code.

Exactly. If the company is winding down anyways, it's hard for things to get worse anyways.

Can't agree more.

Erlang, FoundationDB, there's plenty of success stories of products who were EOL at some point and open sourcing was the thing that made them explode in popularity.

I think Fable is a very-high quality product, it's unfortunate it didn't materialize as a business, but the software has enough quality and popularity to maybe become something like the Blender of that niche; a thing that would be extremely beneficial to any of the founders' future endeavors.