First of all.. lol at AD not even cracking the Top 10. He could possibly get there in 2 years, and likely gets there in 2.5-3.
Emmitt's first 6 seasons -- 8956 yards
Peterson's first 6 seasons -- 8849 yards
I don't think it's far fetched at all to think Peterson finishes in the Top 5 All-Time. Yeah he's had an injury history and has a more violent running style than Emmitt.. but to top LT's mark of 13,684 .. he needs 4,835 yards. If he averaged 1208 yards a season over the next 4 years.. he matches LT's career rushing totals. 1208 yards a season is about 75 yards a game. To top Curtis Martin's spot at #4.. AD could get there in 4 years by averaging 1313 yards a season, or 82 yards a game.
I can see Peterson be in the 1600-2000 yard range for the next 2-3 years before his production drops.. even then, hitting 900-1000 yards in a season (56-63 yards a game) isn't the big deal it used to be. So yeah.. I think he finishes Top 5 barring another major injury.