It really depends on how he wins, and I think that matters in everyone's mind.
Where are you going to rank Brett Rogers among the top ten heavyweights in the world if he is able to pull off the upset of the century over Fedor? Would a win over the consensus number one heavyweight in the world put him in the top spot? In my opinion it would make him at the very least fourth behind lesnar, Nog, and Barnett.
This is a guy who just finished Arlovski, a top ten heavyweight (even in the wake of that loss) in under thirty seconds.
If he stops Fedor, if he does it quickly and decisively and in the first round, it's gonna be hard to argue that he's not a top five heavyweight. Two wins over two decidedly top ten heavyweights, beating them both in the striking, finishing both of them, definitely codifies his position as a top striker.
If he wins a tight decision (which seems unlikely), then he may not break the top five. Still, a win over Fedor, as a prohibitive underdog, would mean a lot.
That said, the odds are not with Brett going into this fight.