It is really hard to predict the short term impact of bitcoin and their price valuation,any news could bring the price of bitcoin and could trigger a sell and the majority of the reason could come up from the uncertainty regarding the network upgrade.
Honestly I do not think those scalability issues are making bitcoin prices fluctuating. Because if we consider scalability issues are impacting market then there would not have any of this much upward rally happened. Traders have ignored scalability issue some long back itself and prices are moving upward just due to Japan's adoption.