Will be interesting to see how the A320 and others in the family mature. Passing time complicates logistics for inserting design changes and maintaining the overall functionality of systems as the airframes age and many individual ones see progressively less thorough maintenance & update support as their value declines.
Electronics and computing technology have accomplished remarkable improvements in density, functionality and performance. For the most part, the art and science of maintaining manufactured versions of these advanced technologies has lagged the pace of application, so that many products just die off when they become unmaintainable. The long lives expected from larger aircraft are not compatible with the philosophy of discarding them at a relatively young age. As the abstraction of fleet age turns into reality, the challenge of keeping the original airframes safe and functional in the field will increase exponentially in difficulty - because of support issues, revision levels, and incompatibilities in the electronics and software of individual units.
Perhaps the most successful support method will be to periodically refurb and "reset" the aircraft to current software rev compatibility by just pulling out all the old electronics & systems and replacing 'em with a full new current set (of pieces that are known to be operationally compatible) one or more times during the airframe service life.