That's part of the problem, there's large catchment areas that don't have an affinity with any team. This used to be the case with Rugby until they concentrated on the provincials.
This is very true and the reason why there's such a huge number of Irish football fans who follow an English team before a team at home. I think it would be still be quite a large following regardless, but there'd be a lot more who would have their Irish team first.
I'm from Athy which footballwise in Ireland was nowhere near a pro/semi-pro team at least in the 80s, so basically my football experience was all from TV, and it was the English league that was the main draw. I don't even remember if the Irish league was televised back then to be honest.