Restricting road capacity even by 1 lane on a Vancouver 6-lane road can have implications on road safety, bus travel times, those who benefit from car-sharing (including emissions-free car-sharing), and general productivity. Restricting on-street parking capacity can and does impact businesses, parking revenue, and amount of off-street parking facilities built and maintained.
I would like to suggest that the reason parking facilities have been reduced downtown is because there are statistics showing that
the amount of car trips into downtown went down by 20% between 1996 and 2006 in spite of population and job growth. Downtown can have reduced parking because there is simply no need for all that parking. That does not mean that the same action would not have been taken if there wasn't such a reduction in car trips. Perhaps parking prices could have risen, but you simply can't take away parking capacity without notice overnight as an attempt to reduce auto use. How did Vancouver get car mode share and trip count down like that then? Simple: by giving people GOOD CHOICES. The Millennium Line SkyTrain expansion and Mk II introduction, the introduction of the B-Lines, the modernization of the bus fleet.... those are all contributors to this.
If you try to restrict without giving good alternatives in return, people aren't going to instantly get out of their cars. They're going to go up in flames and protest and maybe vote against people who would otherwise make good decisions - because what you end up doing is affecting jobs and job options, harming productivity, voter satisfaction, and confidence in government to service needs. In Calgary, confidence in the municipal government and their encourage-park-n-ride model of transportation demand management is slowly declining, because of reliability issues on their C-Trains.
On-street parking doesn't create or define car ownership - it is a response to car ownership. Car ownership (or trip count, whichever applies better) defines the amount of parking. That's why downtown can have parking reductions.
Going back to the idea of bike lanes on Broadway... it is unlikely that they will see much use, because alternate routes on streets far less busy and far better to ride bikes on are one to two blocks away in either direction. I don't think that would be a worthwhile use of municipal funds. It's like having bike lanes at all on No. 3 road in Richmond when the exceptionally wide sidewalk under the SkyTrain guideway is a multi-use path open to bikes... same with 156 St at the Highway 1 overpass in Surrey.
--------
Now, a comment on this "war on the car" mentality here. The war on a car can be a very legitimate concern if auto use growth rate in a particular area is really high, but in other cases I think that some people really need to get out of this battle. It's largely impractical, and becoming even less practical as cars are moving towards becoming a low-emissions or emissions free technology. We even have car share systems that are emissions-free. Cars
can be a part of our world without the harmful effects. What we really need is a balance. Competitive transit should definitely prioritized to promote urban and healthy lifestyle choices, but that doesn't mean make efforts to eliminate the car for its legitimate uses in certain occasions.