Its pretty obvious to me why they wouldn't announce the PC version now if its indeed coming. No real reason benefiting them to do it so its just good business practice to bank on the likely hood a portion of gamers will double dip and buy it again.
For PC gamers like us who would rather play it on the highest end platform but just can't wait, I'd say get it now on console then when its eventually released for PC don't buy it for full price. Wait for a hefty discount. Of course that might be quite some time since Rockstar games retain their value longer than most games but its the right way to go. Besides, games of this size and scope you can go a long time between playthroughs.