At some point, hopefully, they will just announce Red Dead Redemption 2 for PC so that people can play the game instead of sifting through the source code of websites and all sorts of other places looking for hints that it might be coming.
This time it is the web code of Rockstar Social Club that has the latest hint of a PC version. In the source code, RDR2_PC_Accomplishments is mentioned, right next to RDR2_PS4_Trophies. The fact that it is right there next to mentions of another platform makes it highly unlikely that PC stands for playable character in this specific instance. It also seems a lot less unlikely as shortly afterwards the code mentions Player_Arthur instead of PC.
Rockstar hasn’t commented on the matter yet, so if you were waiting for Red Dead Redemption 2 on PC, the wait isn’t over. Possibly not for a long time. Until then, I guess people will keep on digging.