If the known physical laws are not violated, humanity will forever remains in the Solar system. But in the Solar system, apparently, there is nothing principally new and interesting for fundamental science. Perhaps there is only some primitive form of life in atmospheres of the gas giants.
However, to move freely even in the Solar system, we need a velocity at least of about 1000 km/sec. Annihilation of matter and antimatter only is the known source of energy for that a spacecraft of mass of a few hundred tons could reach this velocity. And one needs tens of kilograms of antimatter. This is unlikely to ever become a reality.