Realistically, we probably need energy all of efficiency, renewable boom and nuclear, and more. We should get going as fast as we can, but definitely will not be done in ten years. It is not just electricity that needs to be got off fossil fuels, but also transportation, industry, heating etc. Very likely nuclear power will have roles to play too.

PS. I live in Finland, our electricity is already mostly clean, in large parts thanks to nuclear. Next we will need to clean up heating and industry, probably with a combination of electrification (heat pumps), storage (heat storage, hydrogen), renewables and nuclear.