I don't know, cause of the heat wave or something ;P
well, I don't have any evidence to cite but I guess it's combination of lack of high profile releases on the Vita recently and the anticipation for MH4 (only 2 weeks before MH4 release vita fell below 10k).
I think at that time no one want to buy a Vita when MH4 is releasing soon, getting into MH grinding simply means you won't have time for other games or a new console. Saving for 3DS & MH and following the crowd is more compelling than a Vita with zero attractiveness.
and no the vita won't have a break with the new 2000 release even after MH4 storm, there is a bigger Pokemon storm incoming.
Is the new model even that much of an attractive propersition? I know its lighter and there are new colours but its the same price as the original. Are people really holding out for that?