It might not hit the news, but people are looking into things like how gut microbacteria might affect your brain and behaviour [1]. From what I can see it looks like it is more and more accepted that microorganisms affect us in many different ways.
Xyletol sort of works that way, it looks like sugar to (at least some of) the micro-organisms that like sugar but contains nothing nutritious to them.
Not sure if one can separate the effect prolonged xyletol substitution has on the microbiome from the effect it has on the actual human portion of the metabolism, if one replaces any addiction with something else the original cravings will subside over time.