In the article Nomads of the Galaxy (or this video), it is said that there are possibly 100000x more "free planets" (not orbiting a particular star) than stars. If the size distribution of "free objects" is similar to size distribution of asteroids (some power law - much more small object than large objects), then it could be expected that there are a considerable amount of smaller objects which migrate between the sphere of influence of one star to another.
In such a case it would be better to describe the situation as star system is immersed in some continuum (like gas) of free objects with some non-negligible background density, rather than to speak about discrete Oort clouds. Is there any model or other work which addresses this?
(I'm interested in the connection to the possibility of interstellar travel)
Below is a graphical illustration of my question. Which is more realistic, the upper or the lower chart?