When I look around the world today, I think the biggest resource that is lacking is economic opportunity. Huge swathes of people are desperate, angry, and depressed, I think because there is no opportunity for them. The best case scenario for huge numbers of people is stagnation.
A shrinking, aging population would fix this problem. The demand for labor will go up, the supply will go down. Bad for the investor class looking for profits, good for reducing economic inequality. People will be able to profit from labor again.
The techno utopian solution of allocating everyone a 20 m^2 apartment, a vr headset, and 1500 calories of soylent per day is going to be a disaster unless you also allocate everyone some future drugs to keep them sedated.