"Games are coded on the PC" is a bit of a misleading statement. Games are coded in source code. Whether you do that on Mac, Windows or Linux, and x86, PPC or ARM doesn't really matter. Source code doesn't do anything by itself - it needs an interpreter or a compiler, and these are either themselves compiled to an arch/platform, or compile to an arch/platform. Part of any medium plus sized software development team these days is a remote build process that normalizes build environments between developers, so the development machines themselves don't matter.
The fact the compiler for XBOne and PC may very well be similar isn't really the point. It is far more important that the OS and hardware APIs used in the code are as close as possible. Now, I don't know how close PS4 and XBOne is in this regard, but I'm guessing they are fairly different. So XBOne and PC, both being Microsoft, would probably be much closer, but keep in mind that most MS Windows PCs out there today would be running a version of Windows developed well before the XBOne, and there are a a whole host of other issues to consider as well.
tl;dr - I think people make too much of the arch similarities between the new consoles and PC, when using the argument that it should mean more games for PC. Madden used to be ported from PS2 to PC on the cheap by a 3rd party company for EASports (HeadGate Studios). That's about as different as you can get, but it was still just a matter of rewriting all the API calls and compiling to x86, which is pretty much exactly the same process now days.