While this is a nice thought in theory, it breaks down as soon as you start actually thinking of it in practical terms.
Some rural road that gets a few cars a day at best does not really need sidewalks and certainly does not need bike lanes.
A road with potholes is more dangerous to pedestrians and bikers due to the potential for cars to lose control, or for drivers to swerve to miss a pothole and potentially endanger other travelers.
Adding bike lanes and sidewalks is just impractical in a lot of areas. Where is that space coming from, when private property extends to the road edge currently? Are we just declaring eminent domain and taking 3-6 feet of everyone's property frontage for this initiative? I'm sure that will be a very unpopular initiative. What about areas where buildings are too close to the street to allow for this? There's just too many areas where it's not practical or possible to do.
I'm all for phasing out cars in areas where it's reasonable to do so, but your proposal just isn't compatible with reality.