The best time for a city to invest in making their city walkable and public-transportation-able is decades ago. The second best time for a city to invest in making their city walkable and public-transportation-able is now.
Note that this holds without even having to mention that holding the ability for millions of people to be independent and mobile without needing to purchase and maintain a vehicle against a niche and expensive hobby is ridiculous. But there's no need to bring that up because we can have both.