You realize that no one is making anyone sign long term deals.
The very best players would be looking at 8 year contracts, not 2nd. -> 4th. liners.
The very best players' contracts are exactly what the issue is right now, not the 2nd to 4th liners.
Those guys coming off their ELSC will be 21-23, so an 8 year deal takes them to 31. Players are still in their prime at 31.
Coming off ELSC, it's not uncommon for players to take a briding contract that ends just as they're UFA eligible. It's very hard to accurately judge how a 21 year old will play throughout his prime years. It's best for both sides if the 25-30'ish period is treated separately. By that time, both the team, and the player/agent should have a pretty decent idea of their worth.
Let's say you had to put a $ amount on an 8 year contract for Kadri? What would you say a fair price would be for both sides? How about Gardiner? Do you believe Hall, or Eberle got a fair deal for potential superstars? $6M per season from ages 22-29, and $6M per from ages 23-30, respectively. It's very difficult to say right now, but I think they got low-balled.
If Crosby gets an 8 year deal, it would be hard to see someone like Leino getting 6 years.
Why? A player doesn't need to be a superstar to be valuable to a team. There are a lot of 2nd/3rd liners I'd love to get signed for 5-6 years (assuming that ends up being the max length). Sure, they'd get nowhere near the amount a Crosby would, but I'd be more than fine with having their services for 5-6 seasons.
And as some have pointed out, we're talking a small percentage of players in that level.
That small percentage of the players who have the biggest impact on the game.