trailer is thursday, the announcement image only mentions PS4 and xbox one however no PC port. Guess we'll find out more thursday, I can't imagine NOT having a pc port but it could be like GTA5 where the PC version is 6-12 months later.
RDR on xbone is the 360 version running under BC emulation, it works great though and runs 60 fps solid. If you have an xbone definitely grab it when its on sale, you have a year to play it before RDR 2. You can also get a physical copy (360), pop it in, and play it