From what we know, something like this should be true, but we're still in the process of gathering more information. The true answer, of course, depends on individual habits. If you're using non-biome friendly products, then it's unlikely you could ever get to such a point, but for those foregoing those products, it's likely to get to a point where you have an ongoing "bubble" of AOBs.
Despite this, replenishment is an important part of maintaining a healthy biome. The good bacteria of our skin is constantly in flux based on our environment and what we expose it to. Microorganisms are constantly falling off, scrubbing off, and they definitely don't live forever. It's a natural part of the process. For this reason, it's important to replenish. AOB in the mist (and other good bacteria) don't just grow endlessly. Even our ancestors were constantly "reinoculating" themselves by regularly interacting with the environment (walking barefoot, swimming in lakes, etc).
Does this mean you'll always have to use the same amount of AO+ Mist? Not necessarily. Once again, it depends on your personal habits, environment, and routine. We encourage you to experiment and find what works best for you as time goes on.