It is not, in fact, amazing that the decline of the site's traffic is accelerating. The value of the site as a social network will diminish exponentially for its users as other users leave, just as the usefulness of the site increased exponentially as everyone joined.
The first telephone in the world is no use at all. The second one makes the first one a way for two people to talk; the third, then the fourth and the fifth, increase the possible connections exponentially. But the last telephone in the world is no use either, and as people leave MySpace in a trickle the trickle becomes a flood because the number of possible connections falls below the level that is useful to anyone. The last MySpace account, of course, is no more use than the last telephone. It is only to be expected that the network effect collapses as quickly as once it grew.
I don't expect to talk about MySpace again until they sell it for pennies or close it down.