Well........................
What does appear to be the case is that we now have 2 distinct classes of sprinters, let's say A and B.
Guys from A will win any race without another A entrant, and are consistently sub-10 except for maybe 1 race a year.
A: Bolt, Blake, Gatlin, Powell
There is an A- class, that is either transitional, or the very best of the B:
A-: Vicaut, Dasaolu, Carter, maybe Ashmeade, and maybe some others will emerge this year
Any race in which there is a class A will be won by a class A, unless that class A is out of shape and a class A- gets them.
All the rest are together, relatively (relatively) even, and on any given day, the best of them could win a race, or at least medal, as long as there is no Class A or A- present.
You could say that, well, that is just a normal hierarchy. No. What makes this different is the certainty that a class A will win, and will win going away, and will achieve separation on a field, from which nobody else will unless they are also class A, or A-.