The PC version has existed and was in development with the console versions, we already knew that, Take-Two and Rockstar are just holding it back and most likely repeating a tactic they had with GTAV, where they space out the ports as much as possible in hopes that people will triple dip. For example, the PC port of GTAV was finished at the same time as the PS4/XB1 versions, but still came out six months later, the files showed the game was finalised at the same time and all the updates and patches released on the PS4/XB1 versions were also done as patches on the PC version.