To be honest I think the bottom is going to be around $500. Pretty much everyone I know who is even the slightest bit interested in bitcoin is waiting for this crash to happen so they can jump in. Just a guess though.
[1] http://bitcoincharts.com/charts/bitstampUSD#rg30ztgSzm1g10zm...
The flock of people looking to buy in allow the last group to get out of Bitcoin. Eventually you dry up the well of people who'll be able to bankroll each successive generation of "investors".
There's no commerce going on with Bitcoin on any significant scale, which means it's hugely overvalued. It's just a question of how when the next group looking to buy in on a crash is significantly smaller then the people exiting due to it.