Decline in Registered Pro Riders?

Todays Velonews has an interesting little blurb. It indicates an approximate 40% drop in registered pro riders over last two years. What would explain this trend? Could it be the slow disappearance of organizations willing and able to sponsor pro outfits?? Fewer spot available on pro rosters? The upturn on doping enforcement? The increased cost involved in the entire realm  of professional cycling? Perhaps it's a decline of grass roots opportunities. Maybe it's the X-Box, fast-food, instant gratification environment the youth of today seem to inhabit. What ever the root cause this does not seem to be a positive trend in our favorite pastime.