And if Microsoft decides to kill VSCode, I seriously doubt anyone is going to keep maintaining it at the place where it is now. Even if someone decides to continue maintaining the base editor, Microsoft abandoning it will pretty quickly dry up the plugin ecosystem.
"It's open source, so it will always be available to me" only really makes sense if your backup plan is to maintain it yourself. In the case of VSCode, you are relying on a whole ecosystem continuing to survive after the sponsor abandons it.