is the mitzvah to eliminate a quantity of chameitz or the quality of chameitz: kamus vs. eichus

Boy, is it hard to get back into things after Yom Tov! I’m not sure I’m ready to jump back into blogging – for some reason my brain has a block on putting down anything on paper right now. My son has become a big fan of R’ Yosef Engel’s seforim and spent much of Yom Tov with the sefer Lekach Tov perched in front of him. One of the topics he was delving into was the issue of kamus/eichus, quality vs. quantity and how each plays out in various halachic scenarios. The Rogatchover toys with the same idea in the context of bitul chameitz. What if instead of burning or destroying chameitzdik flour before Yom Tov a person mixed that chameitzdik flour together with pesachdik flour so it was bateil? Leaving aside the issue of using that mixture on Yom Tov, has one fulfilled the mitzvah of tashbisu, of eliminating chameitz, by being mevateil it? On a quantitative basis (kamus), there is still the same amount of flour in the world as there was before bitul took place. But on a qualitative basis (eichus), the chamietz that exists no longer has the halachic status of chameitz. This sounds like a bad pun - can one fulfill bitul chameitz by doing bitul? More later bli neder... I need to ease back into things slowly.