Why would you need to change out brand new batteries?
You would buy a car that had the standardized batteries as original equipment.
There's likely a market for cordless tool battery adapters that let you use currently produced batteries in tools they are no longer marketed for.
I've made my own, but if you could sell a low priced (it's "only" plastic and a little brass/copper) adapter and current production batteries could be had cheaply enough, it may be the impetus for not simply throwing away a set of otherwise nice and functional tools simply because you can't buy batteries with the proper connector.
We seem to have stabilized on 18/20V for the past several years, so that's a plus for the above plan.
