You won’t see the technology used in-air for a while. The USAF only gave Lockheed Martin a contract in 2017, and the first airborne tests aren’t expected until sometime in 2021. It would likely take a while after that before the system could find its way into service.
Provided the technology works as promised, though, it could have a dramatic effect on combat aircraft. The laser wouldn’t be an offensive weapon, at least not at first. Rather, it would be used to shoot down missiles (both air-to-air and surface-to-air). As long as nothing interfered with the laser, an aircraft could be virtually impervious to missile attacks and effectively control the skies.