How big is the market for trust services?

Bigger than one might suppose. According to Walter E. Williams: Only in America:

While becoming a millionaire by age 17 is rare, eventually becoming a millionaire isn't. According to TNS Financial Services' 2004 Affluent Market Research survey, there are an estimated 8.2 million American households with assets, excluding primary residences, worth over $1 million. That's a 33 percent increase over the 6.2 million millionaire households in 2003.

Of course, having a million bucks isn't a certain marker for a trust prospects, is it?