I'm not saying that the 35 isn't an excellent platform, nor am I saying the A10 would be a great asset in a conflict with china, but saying the f35 is a drop in CAS replacement for the A10 is kind of missing the larger picture of what it's used for today.
I am of the opinion that the f35 is a gerber multi tool and while it's super versatile, it doesn't do everything as well as purpose built platforms. The obsession with a one tool fits all is kind of silly. In every category, the f35 is objectively not the winner, there are faster fighters, fighters with greater a2a payloads, CAS with better loiter/payload capacity, bombers with better capacity.
One of the primary goals of CAS should be the ability to stay on station for extended periods of time. Part of the likelihood aircraft are on station is directly related to the cost to maintain and maintenance requirements. F35s have huge costs and require a significant amount of maintenance.