Personally, I suspect the price of Bitcoin is tied to the amount of media coverage related to Bitcoin because of the seemingly strong positive correlation between media coverage and Bitcoin price.
I don't see BIP 16/17 having a significant impact on Bitcoin prices unless implementation somehow has a negative impact on the network, which I don't predict.
I am supporting Tycho on his stance but the network should survive regardless. It is the fear of a problem with implementation I think might be suppressing the price.