Wouldn't Turkey be spiting its own nose if it disallows Russian gas transit though its territory or forces a shift in the transit pipeline plan? Yes, the ceasing of has flow would harm Russia, and the rest of Russia's customers but considering Turkey would collect a toll for every X amount of time or quantity of gas moved through its territory, same as other transit countries like Ukraine, it would deprive itself of a reliable source of revenue. Abandoning the pipeline project would simply shift it elsewhere and again, Turkey would be deprived of both revenue and leverage.
Turkey can cause economic damage to Russia, especially now that Russia needs Turkey more than ever as Europe (Russia's main export market) and Russia feud, but Turkey cannot do so without harming itself either. The best way to respond is simply to put up a strong front, increase your defenses and push forward with your military modernization. Not everything or every action requires an ill-planned response, that's how these conflict start in the first place.
According to Gazprom there are no political affairs holding up or interfering with the proposed Turkish Stream project. UPI reports in an article titled Russia: No political issues with Turkish pipeline.
*I can't post links.
