Whenever people see old systems still in production (say things that are over 30 years old) the assumption is that management refused to fund the replacement. But if you look at replacement projects so many of them are such dismal failures that's management's reluctance to engage in fixing stuff is understandable.
From the outside, decline always looks like a choice, because the exact form the decline takes was chosen. The issue is that all the choices are bad.
Now it is in the best shape ever and progress seems to be unstoppable. And West throughly dominates it in every dimension and that dominance seems to only be accelerating.
Boeing just failed in what was an inherently unfair game: they tried to compete with state-funded Airbus that could just burn unlimited cash not worrying about real profitability, Boeing tried doing it by cutting costs, and failed.