You wonder if this will have a downward pressure on beginning salaries. I haven't really thought this through so I may be missing a few aspects, but teams are now going to be reluctant to sign 18 year old top prospects into the NHL. I could see a scenario playing out where 18 year old top prospects will sign for less to entice teams to sign them as 18 year olds. This probably wouldn't affect a Crosby, but guys like Hartnell, Burns, PM Bouchard, and Connelly. Guys who could have stayed in their respective junior leagues, but their teams thought they were ready or close to it. This could be a deciding factor for teams.
Of course it could have the reverse affect in their second contract at the age of 22-23. Teams are going to want to lock them up for longer than the age 25 while the players aren't going to necessarily be looking for the long-term deal. So I could easily see a team like Atlanta overpaying for Heatley or Kovalchuk's services to keep them off the UFA market until they are 27-29.