Back in the early 80s when Tim and I were students together at Gordon-Conwell the percentage of our classmates who had no intention of pursuing pastoral ministry was startlingly high. Over the years since that percentage has only increased at seminaries across the board.
The New York Times contained an interesting article on the phenomenon last week.
Students with no intention of pursuing pastor ministry aren't the only demographic trend altering the face of modern seminaries. An increasingly-large proportion of seminary populations is comprised of women and second-career 40-plus-year-olds.
It's going to become increasingly obvious in years to come that while seminaries can prepare scholars and parachurch leaders, the Church itself is the best training ground for pastors. Doug Wilson nails this here.