There's no need to add quantum algorithms right now.
The algorithms already exist, if there is any kind of threat, the devs will be able to add the code in a few days.
I don't think it's a big issue really.
The real threat is AI. We can't predict what its moves will be. Especially if it gains self-consciousness. AI can find a way to "break" into Bitcoin, rendering it completely inoperable. Fortunately, Bitcoin can make use of AI to counteract the efforts of rival AIs. The project is open source, anyways.
Once Bitcoin becomes AI and Quantum-Resistant, it will be truly impenetrable. By itself, it's already immortal. As long as someone has access to the source code, there should be nothing to worry about. I'm afraid it's already too late to "destroy" Bitcoin. Wouldn't you agree?