if they limiting it to windows 10 its kind of sucky tho. Rocket league is a game that works on older versions of windows but will the cross play be windows 10 gamers only?
I think what is happening here is because microsoft have released a bad console (losing to ps4), then they are trying to make windows 10 their main platform, it wont happen over night, but its my hunch this is now their long term aim.