Personally, I think these used car batteries will go straight to the dump and will be just another investigative journalism story about how we're damaging the local ecology. Batteries can be recycled but it's fairly expensive, so someone would have to engineer a process that optimizes for time, cost, and life of the battery. As far as I know, nothing exists in mass production like this today.

What I think is more feasible is us finding a way to store energy outside the means of a typical lithium battery. I could very well be idealistic in this sense though.