the master race demolishes the competition once again
actually, both Unreal and Unity are pretty well-known, I think, for their cross-compatibility. both of them can easily be used to make games for PC, consoles, or even phones. not sure about Source, but I imagine it'll be deployable to at least the Xbox One and PS4, so...
nothing has really changed here, except that it's now unbelievably easy to get access to great tools for making games. there's nothing stopping anyone from making these games for non-PC platforms, like it's always been
what the Valve guy said about PC being the "premiere content authoring platform" is pretty meaningless. it always has been, and probably will always be. the alternative would be creating games on a console