Should a student complete his university education or turn to learning a trade, in the event that he is unable to combine the two and is almost certain that there will be no job after graduation?

The fundamental principle for a Muslim is optimism and good expectation of Allah. If one severs hope in Allah, it will be detrimental to them, as happened to the Bedouin who wished for death and consequently died. As for a person feeling that their academic achievement in a particular field is weak, or that employment opportunities are more readily available in other fields, there is no harm in that. Every person is most knowledgeable about their inclinations, capabilities, and the circumstances of their society. Therefore, if you have acquired the individual obligation (fard al-ayn) of knowledge through your studies, there is no objection to abandoning them and pursuing training in permissible crafts if there is a need.