Should cities remove car lanes and parking to build protected cycling infrastructure?
This is very regional specific because it depends on the geography, topography, existing transportation infrastructure, culture, and more.
The existing predominant transportation mode in America being single occupant vehicles is the main barrier, coupled with existing land use practices. It is rare to find communities in america that are truly high-density and multi-use. Suburban sprawl, plazas, strip malls, and commercial centers for lease are inefficient and costly in terms of transportation.
If existing cities or towns were to remove car lanes in favor for bike lanes, the underlying problems would still exist. If bike infrastructure is installed and not used, or is unpleasant to use, then it would all be for naught. For example, a bike path that parallels a highway might be easiest to build, but very uncomfortable if not unhealthy to bike on.
Bike infrastructure has to somehow be integrated within existing site conditions and local municipalities and governments should continue to strive to find these solutions, and be open to them when they present themselves.