Tiger Woods used to be a great golfer, one of the best ever. He's given a lot to the game of golf in terms of its popularity. But let's take a look at the last couple of years.
He hasn't won a major tournament since 2008. In 2009, he was still number one with 6 tour victories and over $10M in earnings. In 2010, his first season after his fall from grace, he had 0 tour victories and ranked 68th. In 2011, he has yet to win a tournament, and hasn't cracked the top 100 in earnings. He has tied for 4th in 3 majors in 2010 and 2011, suggesting that he his game hasn't completely left him. And his big drop this year is largely due to injury and not playing.
I think he will continue to be competitive, but wins will be few and far between. He's won his last major tournament. He'll never be #1 again. I don't think he'll crack the top 5.