Voyager 1 has gone far enough probing the interstellar spaces outside the Solar System, after its Radioisotope Thermoelectric Generators would completely decay the radioactive material inside, the Voyager would then have no option but to shut down, how is the space-craft going to end up in the future when it will run out of its electric supply. Are there any plans to safely dispose off the probe when it will reach its end like the Cassini spacecraft or will they allow it to bump freely into anything?
NASA currently expects that the RTG on Voyager 2 will no longer provide enough power to run a single instrument by 2025. Voyager 1 might last a bit longer. That will be the end of the mission.
Both Voyagers are in a very empty part of space. There is nowhere to crash into, and not enough fuel to change the trajectory noticeably.
Both Voyagers will pass stars at a distance of 1.6-1.7 light years in 40,000 years, and calculations have been made to much longer timescales with no collisions predicted. I don't know specifically if this was deliberate choice, or if it was a happy coincidence of the trajectories chosen for the planetary encounters, but that seems to be 'safe disposal' to me.
Should the Voyagers run into anything, the RTGs were built to survive reentry on Earth, they're pretty robust.