The long term prospects for the integrity of the Roadster and to a lesser extent its seat belted occupant have been addressed in the answers and discussion below Can I drive Elon Musk's Tesla after it's been in space for 100 Years? However, what about the object's orbit itself?
Must said previously that the orbit will be stable for billions of years. Now that its orbit is closer to the asteroid belt, is there a collision risk? Could the proximity to Jupiter change its orbit, sending it flying into the Sun?
After all, Jupiter's influence on other objects in the asteroid belt are well known.