Declining birth rate is directly tied to declining quality of life. There's no one cause but a bunch of interlinked ones. Dealing with climate change would address concerns about the future of the planet. A universal single payer healthcare like pretty much the entire rest of the world has would help with both health concerns and financial concerns. UBI would help with worries about future employment and job market as well as financial concerns. Straight outlawing first past the post voting and enacting some kind of proportional voting system would help address concerns around human rights and democracy. Just an across the board reevaluation of the way the government functions and replacing a number of things that are currently traditions or conventions with actual rules and policies would help with worries about future coup attempts.

At the local level, reevaluation of our approach to zoning and civil engineering would go a long way towards addressing a great many issues around transportation, housing, and the environment.

Pushing for much wider spread adoption of nuclear power would help with climate change, pollution, energy independence, and even international trade.