If you don’t want to see the 300 S Broadway situation repeated, the time to act is now.
The next demolition/redevelopment is already in motion, even if we don’t know where it is, and the next 5 are already in planning. If people want to see the built environment of this city protected, they can’t rely on city regulation and they shouldn’t. People need to take local ownership and they need to improve and protect buildings so they aren’t a case of demolished bunk neglect or get too far to repair for preservation.
There are ways for even people of modest means to take part in investing, like Real Estate Cooperatives, or you can work to support community non-profits to own there own space. Or get groups like your church to take possession for community betterment.
And there are plenty of buildings that are not historic yet but soon will be. In 1950, no one would have thought of the 300 block of S Broadway as special. There were dozens of those buildings if not hundreds. Where is the historic preservation fight of 2040 or 2050? It’s probably a building you ignore every day. It’s probably a house that you could still afford and repair over years.
Is it a perfect solution? No. It is applicable to everyone everywhere? No. But the best time to protect a historic building is almost never ever the day a developer decides to knock it down.