The story forgot to mention Nvidia accidentally mentioning GTA V for PC, and Rockstar Leeds hiring for PC ports of their major upcoming games. Several linked in profiles of Rockstar devs mentioning X360/PS3/PC versions of GTA V. And Rockstar social club on PC update that contained a bunch of GTA V files (quickly removed).
I don't know why Rockstar don't confirm it already...
@TheVoxelman on twitter