More than half of France's nuclear reactors are out of commission right now, so for the foreseeable future that "70%" is more aspirational than anything.

We are obviously not going to meet all of our energy needs — especially for certain high-demand applications — from solar and wind alone, but there are some significant advantages to a decentralized power grid that the pro-nuclear folks don't seem to factor into their arguments. Assuming we can build it out, a decentralized grid ought to be much more resilient to the sort of problems France is facing right now.