A degree or tertiary qualification is definetly worth having. Not necessarily an aviation degree. And yes, perhaps done by correspondence while flying. If you are not too knackered at the end of a long days flying, and have the self discipline to stick it out.
Not everyone "cracks" an airline job. That can really be a bit of a "lottery". Even if you do, I know of more than one person, when interviewed for airlines, who was looked upon as very favourable because of the "peice of paper". Conversely I have often seen people get a good GA job with lower hours because of multi skills. Marketing, Computers, a multitude of things are applicable to aviation and can be used elsewhere as well. You only have to look through some of the technical publications from Australia or internationally and check out the profile of the "execs", the flying ones too, to see who are in these positions.