Irish Whip Fighting has a really ignant ass analysis of the impact of GSP's beat down of Kos on the UFC welterweight division:
I agree about the prospect of a Serra-Koscheck title fight being a nightmare we're better off missing out on. But everything else he says is stupid.
Hughes is old, played out, two-dimensional at best and might not even beat Serra. GSP destroyed him and I think Kos and Fitch would as well. Karo or Diego could easily give Hughes a run too.
And I think after Fitch crushes Diego, he'll go on to beat the winner of Karo/Sakurai (which will be Karo) and will provide GSP a very very tough first title defense.
I might be wrong on every single prediction I just made, but there is no doubt in my mind that Hughes is only the 3rd or 4th toughest fighter in the UFC welterweight division right now.