Which means it can go on for another 15-16 yrs after which it ought to be de commissioned.Average age of two A321s transferred are 14.5 years.
It also makes sense when you consider the fact that given the advances in electronics made every year , you have to upgrade your systems every 8-10 yrs or perhaps even in a lesser time span to stay relevant.
Besides there's a limit to how far one can upgrade ones AEW systems.