The price wasn't exactly going to the moon before the china ban rumor. Total bid sum on Stamp continued to decline and we saw repeated fail pump attempts.
This is going to change if the rumor turns out to be false? Yea right.
If the rumor is false, I expect that the price will go back up to the pre-rumor level (around 3500--3700 CNY or 580--610 USD), and then resume the slow descent from there.
However there may be a permanent residual price drop, due to people becming aware that such a ban is possible in the future even if not right away.