Engineering has gotten more and more complex and difficult over the decades, and it'll continually become more demanding over time, as technological progress develops. Eventually, there'll come a point where the engineers will simply reach the point of burnout. Technical demand will outpace human neuroplasticity and people just won't care to advance civilization anymore.
This act of civilizational resignation will be facilitated by many of the consequences of technological progress itself, that make people less productive:
>social media ramping up women's entitlement and standards, creating an unprecedented incel epidemic and in general ushering in many dysgenic factors that I don't have space to expound on here
>the decline in religion, which will foster depression and/or reckless hedonism; lack of a common morality and religious psychological palliatives will weaken society
>further breakdown of the family structure and easy access to porn, vidya, drugs, etc. will take its toll on productivity
>the capitalist class will resort to opening borders and lowering academic standards to ensure the success of less capable groups of people (e.g. affirmative action, antiracist math)