Hard fork = definitely BTC going below 500, even 500 would be a lot. Without hard fork and if people just agree that hard fork is not likely to happen then price might start rising again. I could see the price of Bitcoin dropping more, but $500 seems too low. I would be very surprised to see that much of a drop unless there is a hard fork.
This HF is nothing more than just a scary dream for weak hands this is trap to get cheap coins. Nothing would be happen to the current mining system it will continue because strong exchanges and mining pools are against this. I don't think price will drop under $900 at any moment.