I do agree that there should be a good space for more than just slash fic in football fandom - but football itself does present one logistical problem: to write het, you either write one of the few male footballer/female footballer pairings (Alex and Serva!) or you're writing characters that are not necessarily celebrities. I obviously am perfectly comfortable with doing this (Claudia Lahm is a major character in one of my fics, after all) but I understand that not everyone is comfortable with that for reasons beyond "ew, het" and more towards "RPF of non-celebrities can be awkward". I think it'd be very different in a non-RPF fandom, or a fandom that doesn't have a gender line sanctioned by the outside (by which I mean FIFA would never take gender blind football seriously - which is its own issue!)

I don't have the answers - I don't know if anyone does, beyond all of us writing what we can - but it is an issue worth exploring.