I think the hype already has died down. There is a cult following dominated by middle aged women (myself among them ) but the younger people I know in the fashion industry would probably pick any number of other things as the "it" bag.
On younger women, a birkin or kelly is kind of a funky "flip" - like wearing your grandmothers bag - the same idea Marc Jacobs' black quilted and gold hardware Chanel take offs is based on.
I think the fact they are so ubiquitous in Manhattan demonstrates this - despite popular perception, fashion-wise most New Yorkers are very careful, not particularly innovative, and somewhat "inside the box" - why else do you think that 80% or more of the clothing you see on the street is black?
As for the price, i think the resale market will cool off but the price at Hermes seems to be resistant to supply and demand - this is probably one of the problems with their business model and why they are not a more profitable company. They are reasonably profitable, but not making a killing, relatively speaking.
Before you flame me, let me make this disclaimer - I am a dyed in the wool birkin fan, and almost never carry anything else - but I am just saying, just because we like it doesnt mean its the height of fashion.