Don't fret!
The beauty of Godot being open source is that even if tomorrow the main/hired developers leave or stop developing, the community can keep updating and improving Godot like nothing ever happened. Almost nothing can stop progress on the engine unless everyone decides to move on and stop using it, because everyone has access to Godot's software code and is free to make their own improvements.
In actual fact, every single release of Godot relies on the work of hundreds of unpaid developers who spend their free time improving the engine because they're awesome and they want to help the project go further.
And even then, nobody here could delete that version of Godot you have installed on your computer. Even if you somehow could never connect to the internet again, that version of Godot on your computer is a fully-fledged game engine and can make a feature-complete game of your design. Some of us are still using past versions of Godot for various reasons and we can still make any game we want to.
The more people we have using and enjoying the engine, the more solid the project is in its foundations. So feel free to make it your home for as long as you like, Godot isn't going to pack up and leave on you.