True, but the NBA is vastly more popular than golf, which helps extend the lifetime brand of Jordan's sneaker sales.
I'm not suggesting that Tiger will necessarily struggle as far as his branding within Nike, but the days of him earning $30+ million per year off the course are becoming less and less practical. And before someone brings up Jack or Arnie, they came from a different time/era and their brands transcended the perceived generational biases, primarily because the people who followed them back in those days are now people 55+ years or older who have much more disposable income than, say, the 30-something with two kids, two car payments and a mortgage today.
The bottom line is that sponsors will always consider the return on their sponsorship investments. Tiger is safe as far as Nike apparel, but beyond that - not much else to hang his hat on.