The landscape of private investigation has evolved dramatically over the previous millennium, and the sector is now poised to make another quantum leap as we transcend into the era of advanced technology and artificial intelligence. This ascension will be significantly driven by the rising tide of digital information, sophisticated surveillance techniques, and cyber forensics. As such, it is paramount to discern the probable trajectories of the private investigation industry to equip ourselves for the impending changes.

Historically, the private investigation business has been characterized by discreet observations, physical surveillance, and comprehensive background checks, typically performed by former law enforcement officers. It was an industry reliant on intuition, subterfuge, and the occasional stroke of luck. However, the advent of the digital age has transformed the tools and methodologies employed by these agents of insight.

The proliferation of social media and other digital platforms has been a game-changer, providing private investigators with a wealth of easily accessible information. Social media forensics, the systematic analysis and study of social media platforms and digital data, is an emerging trend in the field. It involves scrutinizing digital footprints to glean relevant intelligence about individuals.

While this evolution has greatly augmented the efficiency and reach of private investigators, it has also encompassed a slew of challenges. The explosion of easily accessible data translates into an ever-increasing haystack in which to find the proverbial needle. Therefore, investigators must now possess the acumen to analyze substantial amounts of digital information and discern the pertinent pieces.

Artificial Intelligence (AI) anticipates playing a pivotal role in navigating this challenge. AI can be harnessed to parse vast tracts of data swiftly and accurately, a task that would be infeasible for human investigators. Moreover, AI can identify patterns and correlations within the data that may elude human cognition, thereby unearthing insights that would otherwise remain concealed.

Further, biometric technology, leveraging unique physiological characteristics for identification purposes, represents another significant emerging trend. From facial recognition software to fingerprint analysis, these technologies promise to augment the precision and efficiency of private investigators. However, the use of such invasive techniques also raises critical ethical and privacy concerns that must be judiciously addressed.

The future of private investigation also foresees a significant shift towards cyber forensics and cybersecurity. As more individuals and businesses leave an extensive digital footprint, the threat of cybercrime grows correspondingly. Private investigators will increasingly need to address issues like identity theft, fraud, corporate espionage, and cyber-stalking. Hence, expertise in cyber forensics, the process of collecting, analyzing, and preserving electronic evidence, will become a vital skill in the private investigator's toolbox.

The increasing global interconnectedness also suggests an escalating demand for international private investigation. With the world becoming a global village, private investigators will often need to conduct cross-border investigations. This necessitates a comprehensive understanding of international law, foreign cultures, and multiple languages.

The future, however, is not without its uncertainties. The increasing sophistication of AI, for instance, may lead to the automation of a significant chunk of routine investigative tasks. While this could potentially streamline operations and improve efficiency, it also threatens to render certain investigative roles obsolete.

Another critical issue is the regulatory landscape, which is far from settled. Laws relating to privacy and data protection are still evolving, especially concerning emerging technologies like AI and biometrics. Investigators will have to navigate this shifting legal landscape, balancing the need for effective investigation with respect for privacy rights and data protection laws.

In conclusion, the future of private investigation is an exciting amalgamation of opportunity and challenge. While technology offers unprecedented tools and capabilities, it also brings unique complexities and ethical conundrums. However, with the right foresight, adaptability, and ethical compass, private investigators can effectively ride this wave of change and continue to play their crucial role in the society of the future.