So here's my guess at the plot of End Game:
With ~4 billion fewer people on Earth, we're able to quickly reverse climate change, end world hunger, and raise the standard of living for everyone on the planet. The Avengers want to get revenge on Thanos, but instead he gets a Nobel prize. I mean, he can just snap his fingers and make 1,000 Nobel prizes appear, but he appreciates the thought. The end.