Sorry I am late to the party here. I think you have all missed the real reason for the decline of bowling:
People are changing. Part of it is as Russell says, people working more, living further away from those jobs because the housing markets went so high. Then we had 2008, people are out of jobs, people are underemployed, not making the same amount of money they used to. Something has to give and usually it's recreational sports like Bowling. The other thing is people are getting older, the Baby Boomers who were the large influx of ABC/USBC members are getting older. dropping out of the list as they can't compete anymore. And the next generation of bowlers, the youth, have more things to take up their time then ever before. Soccer is more popular than ever in the US. You have so many other activties both outside and inside of the house. Fringe sports are growing, look at the growth of MMA, the growth of golf, etc. Now throw in Playstation, iPad, Xbox360, the growth of the internet and all it brings....the list goes on and on. Where does bowling fit into this? It doesn't. ESPN had a list of the top earners in every sport (the only one I can find is from 2011), Men's Bowling (and this was a good year, when WRW JR earned $152K) came in 36th out 41 sports (Women's bowling was 41st, another sad commentary). What was ahead of bowling....Squash, Professional Eating, Racquetball and even Sumo Wrestling. Joey Chesnut made $218.5K in 2010 for stuffing hot dogs in his face.....and we wonder why bowling can't find sponsors. Bowling is caught in the endless destructive cycle.....maybe if you offered more money for winning, you could get more attention and get more sponsors...but you can't give more money for winning unless you attract more sponsors.
Also, bowling needs to find a new home other than ESPN. ESPN love bowling because it can put it on against the NFL every week, and get better ratings than anything else it can put there. But it's not going to pay for bowling to get a 1 share or whatever it is either. With the proliferation of Network Sports Networks (NBCSport Network, Fox Sports 1, etc) bowling should be able to find a home where it can get a better time slot and see if it can thrive a little. Maybe it is wishful thinking on my part, but it is something that should be investigated.