My initial thought, and it hasn't changed much over the following years, was that Buffy's "Now, you get to choose..." speech would have worked fine IF ALL OF THE REMAINING POTENTIALS IN THE WORLD HAD BEEN PRESENT. And even at that, I think that it would have been a bit more realistic if one or two of the girls there had declined the calling. We were told throughout the season that "the remaining Potentials" were coming to Sunnydale, and that there were "only a few" surviving to get there in the first place. Then we suddenly see girls all over the world receiving their Calling along with the girls there with Buffy. Granted, given the world's total population, a few thousand girls is a miniscule amount, but still, in my opinion, way too many. Remember, the Shadow Men originally created the Slayer to protect their immediate surroundings, not the entire world, and they never envisioned a need for so many girls. In fact, it would have almost certainly been there intention that there NOT ever be more than a single Slayer and a handful of Potentials. To me, it would have been more believable if the actual number of Potentials in the world had been limited to something like 50 per generation, which would have made the few survivors in Sunnydale the entire population of Potentials for that particular generation. Ending up with a Slayer population numbering in the thousands was just wat too many.