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David Richard/Associated Press

We don't like to think about what the NFL will look like without linebackers like NaVorro Bowman, Derrick Johnson or even underrated studs like Thomas Davis; but it will happen. And it'll happen soon.

My generation didn't want to think about an NFL without game-changers like Derrick Thomas or Lawrence Taylor, but along came the next wave of talent in the form of Ray Lewis, DeMarcus Ware and Brian Urlacher. We didn't want the game without Junior Seau or Zach Thomas, but along came Luke Kuechly and Bobby Wagner.

The game moves on, and legends walk away. Looking ahead to the next generation, who will be the best linebacker in the year 2020?

That's what this signature series aims to answer—our "20 for '20" covers who the top 20 linebackers will be five seasons from now. And if you're looking for guys like Bowman or Clay Matthews—who will be well over 30 years old in 2020—we have to project a few retirements and a few slowdowns.