Your question doesn't make sense. Do you have any clue what you are talking about?
Why would there need to be a "single firming capability"? Electricity systems are decentralised. Any becoming more so as we retire big dirty expensive coal and gas clunkers
Why would one type have to system an instantaneous power of 63GW all by itself?
Even China is diversifying it's energy generation and solar and wind are dominating new build
Maybe take the time to read more widely than Sky After Dark, climate science denying blogs and News Ltd?
