I've struggled to get all of my thoughts into one coherent message here, it's a bit rambling, but here goes anyway:
Basically I fear that Celtic and Rangers are historically so inextricably linked to the issues in Northern Ireland that to be honest the problem cannot be solved while the two clubs still exist. You'll never make it just about football, or even limit the conflict to the already-awful levels of behaviour associated with regular football-based rivalries. However many fans of these two clubs simply want to follow a football team, you'll never get rid of the association of each club with a specific side of that religious/political conflict.
Fans of Sheffield Utd and Sheffield Wednesday have a tremendous rivalry, and take great delight in the other club's misfortunes. There are the sets of opposing fans who enjoy the banter, and there are undoubtedly sets of opposing hooligans who go around fighting, beating up supporters of the other team, and giving football a bad name. But in Glasgow, the teams have these ridiculous sectarian trappings, and young fans adopt them without even being properly aware of what they mean.
Fortunately, as a lot of the sectarianism in football is born of ignorance and is genuinely viewed by those partaking in it as part of a football-related rivalry, the bigotry spewed by many fans often lasts only for the duration of the game. Sadly though, because it's roots aren't based in football, there's still a fair few cases where it helps to perpetuate genuine political attitudes and extremism. Football is popular, and people across the nation are encouraged to place their loyalty with one team of their choosing. In the Northeast, kids pick a football team (or are raised to support one) and all that will basically determine for their later life is the colour of the stripes they'll wear on a Saturday. In Glasgow, kids pick a football team (or are raised to support one) and hey presto, by default you've got their political stance on a highly sensitive issue. Peer pressure is a powerful thing, and when you've however many thousand fans seemingly backing one viewpoint, it takes a lot to go the other way.
You can educate and inform, and try to stamp it out, but the clubs will still be their as figureheads for their respective sides in the argument. Their mere existance is a reminder of a social/political/religious divide much older than football, and it'll be an issue in Scottish football until both clubs are disbanded, and a single united "Glasgow FC" is formed. Which will never happen because, well, can you imagine the reaction?