It won't be released on PC, last two were not and why change it now.
There is nothing the PC can offer that can't be delivered by consoles since the launch of the PS4 + and Xbone X
If they were to release on PC, then they would do it on game release. PC has become expensive for R* to maintain if their is an online component with RDR2. GTA V was unique in so far as it released before next gen consoles went on sale. So when it was finally released on new gen a PC release was inevitable as online was to be ramped up and old gen left behind. People bought the game again for whistle n bells and online content.
However, the anti cheat costs have been all PC for the past 2 years and why would R* or take2 most likely, want to keep having to burden the cost of PC ongoing when they can concentrate on the two consoles. Yep, they did well with GTA V (80 million copies) but they must be bored of trying to manage the game from the PC side of things.
So no, Red dead is and will continue to be a console exclusive.