It won't happen over night
What seems to have spiked interest in the past towards pool was the release of the movie "The Hustler". That was in the early 1960's. In the mid 1980's, when "The Color of Money" was released, interest in pool spiked again. Prior to both of those movies, the last big surge in interest was when WW2 ended and the returning GI's came back with memories of having gambled at pool while on leave. That brief upswell stagnated quickly.
What was the common denominator here....something happened that affected large masses of people. Not to sound stupid, but there is NOTHING happening right now that is all that special in pool, except for us die hard fans and lovers of pool. With all the new technology like X-box, and those crazy electronic gadgets, more people are willing to sit on a floor and play Nintendo baseball rather than go outside and PLAY REAL baseball. Pool is not the only sport that is in decline right now in America.
Bowling has been decling for years. In other countries like Taiwan and China, interest in pool is on the upswing. Why? Because those countries are funding pool related teaching and tournaments in their schools. Can you imagine going to your local school board and petitioning for them to allocate funds for a "pool program"?
There's not going to be a quick fix here. One thing that I think would help is for a dominant, and I mean DOMINATING player to come forth. One with some type of pizzazz or razzmatazz that would attract the average couch potatoe's short attention span. If the networks would feature him on say a Wide World of Sports, or a CBS Sport's Spectacular, or NBC Sportsworld, well then...wait. Umm, all those programs are long gone. And that's one of the reasons why boxing is also on the downside. Not a lot of free TV anymore. The ESPN boxing match ups are usually not between established champions.
I'll end this very long winded soliloquy by saying that if all of us true fans would start inviting others out to shoot some pool with us, and then keep at it, then we may be able to strengthen the fan base a little, but it will take something unexpected to get another real surge in popularity. I have hopes that it will happen. If not, does anyone here remember the old Balkline billiards? It was popular in the the early part of the last century. All but extinct now....