The original post was complaining about increasing density and how investment in public transport hasn't kept up. The previous poster said what about bikes, and you are now saying that bikes are not a solution to people coming from the greater Paris region. But that was not what we are talking about, we were talking about higher density (=more people) in Paris proper. Bikes are certainly a solution to transport in the high density city.
Only part of my answer was about people coming in from afar. The other, about there being nowhere to store bikes, as well as questionable quality of the biking infrastructure is about the city itself.
Edit: I'm actually saying this as someone who enjoys and actually does bike. When living in the city proper, I think there are very few routes for which the bike isn't the quickest method of transportation. For my commute, which is pretty much a best-case scenario (modern metro with few to no issues, goes in a fairly straight line, don't have to change lines, stations close to both home and the office) the bike is much faster: 20 instead of 30 minutes.
Bike storage was never a problem for me living in London, even when I lived on a tiny canal boat. I can’t imagine Parisian’s bicycles are that different nor their homes much smaller than a boat or my 75m2 flat. Yes, I also have a cargo bike for transporting kids. The only thing stopping anyone from cycling is their anxiety and sense of car-owing identity
I was talking to a friend living in London, and it would indeed seem that flats tend to be bigger over there. We do have many 100+ m2 flats, don't get me wrong, it's just that most locals can't afford those and live in shoeboxes instead.
There's also the fact that the layout doesn't always lend itself to storing a bike, most flats being rather old. Even though I would technically have the surface area to store a bike, it'd have to be in an awkward place to avoid blocking the passages.
Some newer apartment buildings do have areas for storing bikes more or less securely. But I doubt that's the case for most people.
Instead, what I'm hopeful for, is that the local bike-sharing scheme will improve. And indeed, I've read a few weeks ago that they were rolling out some improved model, which they expect to be more robust.
