Some 43 per cent of wealthy business owners say they plan to work until age 70 or longer, according to a new national survey by PNC Wealth Management, part of the Pittsburgh-based PNC Financial Services Group. This is double the number polled for comparably affluent Americans who do not own a business. More than half of those who plan to work until at least age 70 said it's because they enjoy working. But only one-third of those business owners have a written succession plan, even though 54 per cent are in business with family members. PNC surveyed 600 affluent business owners with median investable assets of $1.34 million.