I think American cities will continue to see more bike usage, but probably driven more by the fact that it's way less expensive to own a bike rather than being more convenient or useful.

Once a city reaches a critical mass of bikers, infrastructure will probably improve and then it may in fact become more convenient and useful to bike places.

But most drivers in places with no bike infrastructure hate bikers, so I think there will be some major pushback along the way.

My suspicion is that the bulk of health discrepancies between Europe and the US is just exercise. Obesity in Pennsylvania would be like in France if people walked and biked as much.