IMHO, I think that the major airlines in the US place far too much emphasis on the 4 year degree requirement. However, as that is not likely to change anytime soon, it makes sense to obtain a 4 year degree if your ultimate goal is to fly for one of them.

Outside of the US, airlines generally take a more pragmatic view with their hiring criteria. Having the right attitude and the right experience is considered more important than holding a formal tertiary qualification.