I am not sure it's on the bottom at the moment, people are assuming that it's China only. However, there are a lot more factors involved which are bringing up or down such as (current):
On the negative side:
1) Starting with MTGOX, I think we all know the story which brought it down almost to half.
2) Chinese government preventing it's banks from using Bitcoins etc.
3) A state in America banning Bitcoin transactions in wine-trading due to younger age etc.
4) Boris Johnson (UK) announcing that the currency is untraceable and used in all sorts of criminal activities when abroad etc.
5) Google removing some apps (screen savers) after discovering they have malware to do BTC mining.
6) Amazon not wanting to use it due to huge fluctuations in the US/BTC rate when interviewed.
On the positive side:
1) MTGOX's story about the currency being vulnerable to forging seems to have no real base, some speculations of; most likely he took-off with the money and filed for bankruptcy...
2) Banks in the US introducing the first BTC machine to use it publicly.
3) Some worldwide stores and traders are starting to accept BTC.
Now, theories that might be said to take it "really" down or cause havoc:
1) What if MTGOX theory of someone forging a BTC (i.e. copying it to many or something) is actually correct?!... Just imagine someone pumping BTCs into the market to dry out USDs?!..
2) What if another government decided to ban the use of it just like what China did?
3) What if China decided to "Oh you know what!?... We LOVE BTCs, who said anything about Banning?!
"...
4) What if China have decided to make it's own BTC instead?!... I know... long shot, but what it?!...
5) Litecoin around the corner growing up ?!...
Anyway, please don't think that after this downturn that things are going to be hunky-dory,.. there is a lot going on at the moment and yet nobody knows the future for sure.
Stay wise, that's all I would do for now... Or, use the force Luke...
Regards
Heider