But none of the suggestions would increase the density of aircraft around major airports. They're already operating at runway capacity during peak times.
As described, there is a lot of tedium, inaccuracy, and potential for human error in the ATC system. They're passing strips of paper back and forth, and making sure that no two strips put two planes in the same spot, and relaying the information over verbal radio commands.
It's begging to be automated.
I know very little about the financial end of things, or what would or would not solve the problem, but it does seem like a saner funding system would go a long way. Most people I've spoken to here seem skeptical at best about suggestions of breaking us off from the FAA.
But it doesn't rise to the level of the title "how to fix flying". The current system, for all of its warts, has proven to be amazingly safe.