Solid-state batteries might not be cheaper at first. But once economies of scale from mass production efficiencies kick in, they will be.
One thing that goes under-appreciated about EVs is that even though they are winning today against gas-cars on reliability and cheapness, they still have years of improvements and cost reductions ahead. By the 2030s, they will be vastly cheaper & better than fossil fuel cars.
China is already making decent cars in the $10-15k price range; this battery tech will make that even easier. It's also making these cars with good Level 3 self-driving tech. There is a vast unserved market in the Global South (& huge chunks of the Western world) for cars like this.
The standard global car of the 2030s will be Chinese-made, an EV, self-driving & cost about $10,000. Anyone who still thinks gas cars have a future in this world is a dinosaur who can't see that asteroid streaking through the sky & about to hit them.
Solid-state EV batteries are coming sooner than expected after another breakthrough
I mean, great, if it makes a dent in fossil fuel use. It doesn't solve the car issue itself, though, just puts a patch on it. And to quote the well-known "Newsroom" episode, "that would have been great... 20 years ago."
Anything is better than nothing. Just don't celebrate too much, keep it at the level it deserves.
More to the issue is that we've designed so much of our planning and scapes around being able to turn an hour walk to get something done, to a ten minute chore from our doorstep. Cities used to have nets of smaller shops around neighbourhoods, now its a distant complex built to be hostile to pedestrians.
I don't know how we fix that in some places, even with public transport, but we may as well take one win if it helps us as a civilization at all