Mortal Kombat X launched on PC the same day as consoles. The PC version has received all the DLC to date, including post-launch/non Kombat Pack 1 DLC. Therefore, logic dictates this next batch of DLC will come to PC.
Is it possible it won't? Sure, but people are basing all this off the absence of the Steam logo in two trailers. That is not proof, and people are blowing things way out of proportion.
Using the same logic, the new Pit stage won't launch on any platform because it's not mentioned in the Kombat Pack 2 content listing.