Paved bicycle paths require a fraction of the size and an even smaller fraction of the upkeep, on account of bicycles being so light, and road tear being an approximate function of weight to the fourth power.

If you want everyone to bike, you'll need larger bikeways than what exists now.

Also, you'll still need the roads for logistics.

Bicycle infrastructure accomodates far more people per area of infrastructure, as cars scale really poorly while bicycles scale really well.

My point about maintenance also still stands.